MASS TRANSFER OPERATIONS LAB (ChE-306L) Lab Incharge: Ms. Kanwal Shabbir Graduate Assistant: Engr. Anees Ahmad
Department of Chemical Engineering University of Engineering and Technology, Lahore
Contents
List of Possible Hazards in M.T.O. Lab ...............................................2 The COSHH Regulations ......................................................................3 Water-Borne Infections .........................................................................4 Use of Residual Current Device as an Electrical Safety Device ..........5 Lab Note Book Rubric ..........................................................................6 Experiment Performance Rubric ...........................................................7 Equipment Status in Mass Transfer Operations Lab ..........................10 List of Consumables for Mass Transfer Operations Lab ....................12 List of Glass Wares for Mass Transfer Operations Lab .....................14 Equipment Detail Manuals ..................................................................17 Lab Manuals (Experiments) ............................................................. 104 Lab Flexes ........................................................................................ 173 Material Safety Data Sheets for Chemicals ..................................... 187
Page - 1
List of Possible Hazards in M.T.O. Lab
Following are the potential hazards and their remedies:
S. No. 1
2
3
4 5
Potential Hazard
Mitigation
Circuit breakers are installed with equipment to avoid any personal or equipment damage. Chemical Hazards 1. Latex gloves and lab coat is 1. Acid / Alkali solutions are strongly corrosive. recommended to avoid any 2. Acid may splash vigorously. contact with these chemicals. 3. Organic chemicals are volatile (form vapors 2. Slow addition of acid drops fast). in water is recommended. Biological Hazard Retained water in tanks of equipment may Immediate draining of tanks is allow the growth of legionella Pneumophila and recommended. other water borne microbes. First aid kit is recommended for Injury from sharp glass objects. lab. Electrical Hazard
Fire: 1. Organic vapors can cause fire. 2. Electrical short circuit can cause fire.
6
Accidental Acid or Alkali release.
7
Accidental contact of non-compatible chemicals.
Fire extinguisher is recommended. 1. Immediate evacuation of lab is recommended if release is severe. 2. Acid / Alkali must be neutralized with its counterpart. 3. Spillage must be confined in affected area only. 1. Organic chemicals should not be kept near fire or spark. 2. Acid should not come into contact with pure metals.
Page - 2
The COSHH Regulations The Control of Substances Hazardous to Health Regulations (1988) The COSHH regulations impose a duty on employers to protect employees and others from substances used to work which may be hazardous to health. The regulations require you to make an assessment of all operations which are liable to expose any person to hazardous solids, liquids, dusts, vapors, gases or micro-organisms. You are also required to introduce suitable procedures for handling these substances and keep appropriate records. Since the equipment supplied by Armfield Limited may involve the use of substances which can be hazardous (for example, cleaning fluids used for maintenance or chemicals used for particular demonstrations) it is essential that the laboratory supervisor or some other person in authority is responsible for implementing the COSHH regulations. Part of the above regulations are to ensure that the relevant Health and Safety Data Sheets are available for all hazardous substances used in the laboratory. Any person using a hazardous substance must be informed of the following: Physical data about the substance Any hazard from fire or explosion Any hazard to health Appropriate First Aid treatment. Any hazard from reaction with other substances. How to clean/dispose of spillage. Appropriate protective measures. Appropriate storage and handling. Although these regulations may not be applicable in your country, it is strongly recommended that a similar approach is adopted for the protection of the students operating the equipment. Local regulations must be considered.
Page - 3
Water-Borne Infections
The equipment described in this instruction manual involves the use of water which under certain conditions can create a health hazard due to infection by harmful microorganisms. For example, the microscopic bacterium called Legionella pneumophila will feed on any scale, rust, algae or sludge in water and will breed rapidly if the temperature of water is between 20 and 45°C. Any water containing this bacterium which is sprayed or splashed creating air borne droplets can produce a form of pneumonia called Legionaries Disease which is potentially fatal. Legionella is not the only harmful micro-organism which can infect water but it serves as a useful example of the need for cleanliness. Under the COSHH regulations, the following precautions must be observed. Any water contained within the product must not be allowed to stagnate, i.e. the water must be changed regularly. Any rust, sludge, scale or algae on which micro-organisms can feed must be removed regularly, i.e. the equipment must be cleaned regularly. Where practicable the water should be maintained at a temperature below 20°C or above 45°C. If this is not practicable then the water should be disinfected if it is safe and appropriate to do so. Note that other hazards may exist in the handling of biocides used to disinfect the water. A scheme should be prepared for preventing or controlling the risk incorporating all of the actions listed above. Further details on preventing infection are contained in the publication “The Control of Legionellosis including Legionnaries Disease”- Health and Safety Series booklet HS (G) 70.
Page - 4
Use of Residual Current Device as an Electrical Safety Device
The equipment described in this instruction manual operates from a mains voltage electrical supply. The equipment is designed and manufactured in accordance with appropriate regulations relating to the use of electricity. Similarly, it is assumed that regulations applying to the operation of electrical equipment are observed by the end user.
However, it is recommended that the RESIDUAL CURRENT DEVICE (RCD) supplied (alternatively call an EARTH LEAKAGE CIRCUIT BREAKER -ELCB) be fitted to this equipment. If through misuse or accident the equipment becomes electrically dangerous, an RCD will switch off the electrical supply and reduce the severity of an electric shock received by an operator to a level which, under normal circumstances, will not cause injury to that person.
If the electrical supply to the laboratory already incorporated an RCD, then the device supplied with the equipment need not be used. If the electrical supply does not incorporate such protection, then the loose RCD supplied by Armfield Ltd. Should be fitted by a competent electrician either in the supply to the laboratory or in the supply to the individual item of equipment.
NOTE: If any doubt exists whether the electrical supply incorporates a device then RCD supplied should be fitted.
At least once each month, check that the RCD is operating correctly by pressing the TEST button. The circuit breaker MUST trip when the button is pressed. Failure to trip means that the operator is not protected and the equipment must be checked and repaired by a competent electrician before it is used.
Page - 5
Lab Note Book Rubric
Excellent (2)
Completion
1. All experiments are written completely and results interpreted. 2. Graphs, tables and suggestions are mentioned.
Timely Response
Copy is submitted at least one day before oral evaluation (viva).
All experiments are concluded with correct interpretation of Comments / results and any discrepancy in Suggestions procedure or equipment is pointed out and correction proposed. 1. Sources of error are correctly identified. 2. Proper tools e.g. regression Sources of analysis is used to quantify Errors the magnitudes of errors. 3. Effect of errors on results is correctly interpreted. 1. A standard format is followed for writing all experiments. Organization 2. Index of performing all / experiments is available at Presentation the start of the notebook of Contents along with the date of performing the experiment. 3. Graphs, tables are captioned properly and attached.
Satisfactory (1) All experiments are written completely and results interpreted. Copy is submitted at the end of the semester within given timeline from lab instructor. At least all experiments are concluded with correct interpretation of results.
At least procedural / equipment errors are identified.
Unsatisfactory (0)
Score
Experiments are incomplete.
Submission do not comply with the given time domain.
Objective of performing experiment is not clear.
Errors are not identified and reasons are unknown.
Haphazard presentation Overall neat look is lacking any comaintained. ordination between contents.
Total Scores
Page - 6
Experiment Performance Rubric
Excellent (4)
Attendance
100 %
Punctuality
Always on time in 95% labs at least.
PreExperiment Activities
1. Calibration checks of equipment. 2. Rinsing and washing of apparatus. 3. Clear procedural understanding. 4. Preparation of solutions / chemicals / accessories for experiment. Active participation in:
1. Keeping workplace clean. 2. Collection of Participation data. 3. Proper handling of equipment / chemicals. 4. Cooperating with team members. 1. Proper cleaning / washing of items. Post 2. Safekeeping of Experiment items and Activities accessories. 3. Proper waste disposal of chemical.
Good (3)
Satisfactory (2)
1. 90% at least. 2. In case of leaves, lab work is compensated. Always on time in 90% labs at least.
1. 80% at least. 2. In case of leaves, lab work is compensated. Always on time in 80% labs at least.
Below average (1) 1. 75% at least. 2. In case of leaves, lab work is compensated. Always on time in 75% labs at least.
1. Calibration checks of 1. Rinsing and equipment. washing of 2. Rinsing and Clear apparatus. washing of procedural 2. Clear apparatus. understanding. procedural 3. Clear understanding. procedural understanding.
Unsatisfactory Score (0) 1. Below 75%. 2. In case of leaves, lab work is not compensated. On time in less than 75% labs at least.
No understanding of any experimental activities.
Active participation in: 1. Keeping workplace clean. 2. Collection of data. 3. Proper handling of equipment / chemicals.
Active participation in:
Active participation in:
1. Keeping workplace 1. Collection clean. of data. 2. Collection of data.
1. Proper cleaning / washing of 1. Proper items. cleaning / 2. Safekeeping of washing of items and items. accessories. 2. Safekeeping 3. Proper waste of items and disposal of accessories. chemical.
Proper cleaning / washing of items.
No active participation in lab activities.
No participation in post experiment activities.
Page - 7
Safety
Result Calculation
Discussion on Results
Graph / Statistical Analysis of Data
Analytical Thinking
4. Proper shut down of equipment. 1. All possible hazards are evaluated. 2. Proper functioning of safety parameters is evaluated. 3. PPE’s are used properly. 4. MSDS are consulted and Lab safety form is filled countersigned by lab instructor. 1. Proper data is collected from experiment. 2. Erroneous readings / trends in data are identified. 3. All results are calculated. 4. Unit consistency is maintained. Results are: 1. Accurate 2. Precise 3. Reproducible 4. Presentable Data / Results are presented in: 1. Graphical form. 2. Statistically analyzed e.g. trend lines regression coefficients added. 3. Errors marked graphically. 4. Graphs properly captioned. 1. Objectives of experiment are fully grasped.
1. All possible hazards are evaluated. 2. Proper functioning of safety interlocks is evaluated. 3. PPE’s are used.
1. Proper data is collected from experiment. 2. Erroneous readings / trends in data are identified. 3. All results are calculated.
Results are: 1. Accurate 2. Precise 3. Reproducible
1. All possible hazards are evaluated. 2. Proper functioning of safety interlocks is evaluated.
All possible hazards are evaluated
1. Erroneous readings / trends in data are identified. 2. All results are calculated.
All results are calculated.
No results calculated.
Results are accurate.
No idea has been built from data and results.
Results are: 1. Accurate 2. Precise
Data / Results are presented in: Data / Results are 1. Graphical presented in: form. 1. Graphical 2. Statistically form Data / Results analyzed e.g. statistically are presented in trend lines analyzed e.g. graphical form. regression trend lines coefficients regression added. coefficients 3. Errors marked added. graphically. 1. Objectives of experiment are fully grasped.
1. Objectives of experiment are fully grasped.
Objectives of experiment are fully grasped.
No possible hazard evaluation is done.
No graphical / statistical manipulation of data.
No idea is built from experiment.
Page - 8
2. Idea from 2. Idea from experiment can experiment can be applied to be applied to other physical other physical situations. situations. 3. Any betterment 3. Any betterment to current to current procedure is procedure is proposed. proposed. 4. One has developed theoretical understanding of concept.
2. Idea from experiment can be applied to other physical situations.
Total Scores
Page - 9
Equipment Status in Mass Transfer Operations Lab
S. No.
1
2
3
4
5
Equipment
Ion Exchange Apparatus
Gas Diffusion Coefficient Apparatus
Continuous Distillation Apparatus
Batch Distillation Apparatus
LiquidLiquid Extraction Apparatus
Remarks
Recommendations
1. Pump is defected.
1. Repair Pump.
2. Extensive Leakages in all Joints.
2. Use Epoxy (Resin + Hardener) Adhesive. 3. Need to be replaced of whole unit. Due to very bad condition.
3. Plastic Pipes are causing leakages. 4. Clumps are not present with tubing and causing leakages.
4. Purchase Clumps
1. Capillary Tube is damaged at entrance.
1. Purchase new.
2. Leakages in Water Tank.
2. Use Epoxy (Resin + Hardener) Adhesive
1. Boiler heater is causing noise formation above 100oC. 2. Boiler Level Sensor is permanently damaged. 3. Thermocouples are problematic.
Place of Availability
Max. Expected Price
-
Rs. 2000
Brandth Road LHR.
Rs.100
Brandth Road LHR.
Rs. 965
Brandth Road LHR.
In Search
Abkari Road LHR. Brandth Road LHR. Need to be inspected thoroughly.
Need to be inspected thoroughly.
2. Replace Level Sensor.
In Search
In Search
3. Replacement of Thermocouples.
In Search
In Search
-
-
1. Replace Boiler Heater.
1. Thermocouples are inaccurate.
1. Re-Calibration is needed.
1. Solvent Pump is Problematic.
1. Repair Solvent Pump (Repairable)
2. Electrodes are not working.
2. Replace Electrodes
3. Leakages in water tanks.
3. Replace Tanks.
4. Distillation section is not working.
4. Unidentified. (After repairing all other parts of this equipment, the problem can be identified).
Rs. 100 Rs. 100
From Any Motor, Mechanic In Search Shahalam Market LHR.
In Search
Need to be inspected thoroughly.
Need to be inspected thoroughly.
Rs. 1000
In Search
Page - 10
6
7
8
Gas Absorption Column Apparatus
Tray Drier Apparatus
Fluid Bed Dryer Apparatus
1. Extensive leakages in the column. 2. Manometers are not working. 3. Column is chocked at a specific point.
1. Column need to be replaced due to very extensive leakages. 2. Replacement of Manometers. 3. Packing needs to be refiled. (New packing is not required).
1. Weight Balance is not working.
1. Replace Weight Balance.
2. Psychrometric Gun is Problematic.
2. Replace Psychrometric Gun.
1. Equipment is burned from inside the unit.
1. It needs to be checked from inside the unit. (Need an expert person).
Abkari Road LHR.
In Search
Abkari Road LHR.
In Search
-
-
Shahalam Market LHR. Need to be inspected thoroughly. Need to be inspected thoroughly.
Rs. 500 to 1000 Need to be inspected thoroughly. Need to be inspected thoroughly.
Page - 11
List of Consumables for Mass Transfer Operations Lab S. No. 1
2
3
4
Chemicals Acetone Cation Exchange Resin
Anion Exchange Resin
HCl
Equipment Gas Diffusion
Ion Exchange
Ion Exchange
Ion Exchange
Experiment Experiment-1 Experiment-2 Experiment-3
Experiment-2 Experiment-3 Experiment-2 Experiment-3
Required
Available
Quantity
Quantity
2 liter
0 liter Sufficient
0 kg
Quantity is Available Sufficient
0 kg
Quantity is Available
1 kg
0 kg
1 kg
0 kg
1 kg
0 kg
1 kg
0 kg
20 liter
0 liter
45 liter
0 liter
20 kg
0 kg
200 gram
0 gram
Experiment-2 Ion Exchange 5
NaOH
Gas Absorption L-L Extraction
Experiment-3 Experiment-9 Experiment-10 Experiment-11 Experiment-12
6
Ca(OH)2
Ion Exchange
7
Mg(OH)2
Ion Exchange
8
Distilled Water
Ion Exchange
Experiment-2 Experiment-3 Experiment-2 Experiment-3 Experiment-2 Experiment-3 Experiment-4
9
Ethanol
Batch Distillation Conti. Distillation
Experiment-5 Experiment-6 Experiment-7 Experiment-8
10
CO2 Gas
Gas Absorption
11
Phenolphthalein
Gas Absorption
Experiment-9 Experiment-10 Experiment-10
Page - 12
L-L Extraction
Experiment-11 Experiment-12
12
NaHCO3
Gas Absorption
13
Propionic Acid
L-L Extraction
14
Trichloroethylene L-L Extraction
15
Sand
Tray Drier
Experiment-10 Experiment-11 Experiment-12 Experiment-11 Experiment-12 Experiment-13 Experiment-14
1 kg
0 kg
5 liter
0 liter
20 liter
0 liter
5 kg
0 kg
Page - 13
List of Glass Wares for Mass Transfer Operations Lab S. No. 1
Item Beaker (500 ml)
Equipment Ion Exchange
Experiment Experiment (2, 3)
Required Available Quantity
Quantity
0
2
0
1
0
4
0
6
Batch Distillation 2
Beaker (400 ml)
Conti. Distillation Gas Absorption
Experiment (4,6,7,8,10,11,12)
L-L Extraction Batch Distillation 3
Beaker (250 ml)
Conti. Distillation Gas Absorption
Experiment (4, 6, 7, 8, 10, 11, 12)
L-L Extraction Batch Distillation 4
Beaker (100 ml)
Conti. Distillation Gas Absorption
Experiment (4, 6, 7, 8, 10, 11, 12)
L-L Extraction 5
Beaker (50 ml)
Ion Exchange
Experiment (2, 3)
0
1
6
Beaker (10 ml)
Ion Exchange
Experiment (2, 3)
0
2
7
Glass Stirrer
Ion Exchange
Experiment (2, 3)
2
0
0
1
1
0
Experiment-5
0
2
Experiment (2, 3)
0
2
Measuring 8
Cylinder (500 ml)
Measuring 9
Cylinder (250 ml)
Batch Distillation Conti. Distillation Gas Absorption
Experiment (4, 6, 7, 8, 10, 11, 12)
L-L Extraction Batch Distillation Conti. Distillation Gas Absorption
Experiment (4, 6, 7, 8, 10, 11, 12)
L-L Extraction
Measuring 10
Cylinder
Batch Distillation
(100 ml) 11
Measuring Cylinder (50 ml)
Ion Exchange
Page - 14
12
Measuring Cylinder (25 ml)
Ion Exchange
Experiment (2, 3)
0
1
2
0
0
1
Batch Distillation 13
Stop Watch
Conti. Distillation Tray Drier
Experiment (4, 6, 7, 8, 13)
Fluidized Bed Drier 14
15
16
17
18
19
20
21
22
23
Hand Held
Batch Distillation
Experiment (5, 6,
Refractometer
Conti. Distillation
7, 8)
Funnel
Gas Absorption
Experiment-9
2
0
L-L Extraction
Experiment-11
0
3
Pyrex Bottle
Ion Exchange
Experiment (2, 3,
(1000 ml)
Gas Absorption
0
1
(Small Size) Funnel (Medium Size)
Pyrex Bottle (500 ml) Pyrex Bottle (250 ml)
26
Experiment (2, 3)
0
1
Ion Exchange
Experiment (2, 3)
0
1
0
1
0
2
0
1
0
4
0
2
Gas Absorption
Experiment (10,
Rubber Bulb
L-L Extraction
11, 12)
Gas Absorption
Experiment (10,
L-L Extraction
11, 12)
Ion Exchange
Experiment (2, 3)
Burette (50 ml) Conical Flask (500 ml) Conical Flask
Gas Absorption
Experiment (10,
(250 ml)
L-L Extraction
11, 12)
Gas Absorption
Experiment (10,
L-L Extraction
11, 12)
L-L Extraction
Experiment-11
Ion Exchange
Experiment (2, 3,
2
10, 11, 12)
(Urgent)
Stoppered Flask (125 ml)
25
Ion Exchange
Pipette with
Conical 24
10)
Separating Funnel (250ml) Iron Stand
Gas Absorption
2 (Urgent)
0
0
Page - 15
L-L Extraction Gas Diffusion 27
Thermometer
Tray Drier Fluid Bed Drier
Experiment (1, 13, 14, 15)
10
1
Page - 16
Equipment Detail Manuals
1. Gas Diffusion Coefficients Apparatus 2. Ion Exchange Apparatus 3. Batch Distillation Apparatus 4. Continuous Distillation Apparatus 5. Gas Absorption Column Apparatus 6. Liquid-Liquid Extraction Apparatus 7. Tray Drier Apparatus 8. Fluidized Bed Drier Apparatus
Page - 17
Instruction Manual
GAS DIFFUSION COEFFICIENTS APPARATUS
Page - 18
INTRODUCTION Physical and chemical processes depend on the properties of the materials involved. Process engineering concerns itself with the transformation and distribution of materials in bulk. The design and operation of engineering plant to achieve the desired changes in materials has therefore to take into account the physical and chemical properties of these materials. The most convenient medium is the fluid state, and hence the majority of plant operations involve gases or liquids. One of the most important properties of fluids in such situations is diffusivity. Fluid flow and mass transfer operations depend partially on this property and such data is always needed in plant design. The Gaseous Diffusion Coefficient Apparatus allows students to measure to a reasonable degree of accuracy this property, by a well-established technique. This practical exercise involved in this measurement allows students an introduction to handling the basic equations of mass and momentum transfer, and is a complement to, rather than a substitute for, the more exacting measurements made by physical chemists.
Page - 19
DIAGRAM
Page - 20
DESCRIPTION Parts of Equipment 1) Glass Thermometer 2) Capillary Tube 3) Temperature Sensor 4) Compartment 5) Lever Operated Cock 6) Adjustable Feet 7) Cartridge Element 8) Vernier Height Gauge 9) Removable Support Stand 10) Microscope 11) Adjustable ON/OFF Temperature Controller 12) Left-Hand Switch 13) Integral Cable 14) Right Hand Mains Switch 15) Compartment 16) Float Switch 17) Flexible Tube
Brief Description The equipment consists of an acrylic assembly which is sub-divided into two compartments. One compartment is constructed from clear acrylic and is used as a constant temperature water bath. The other compartment incorporates an air pump and the necessary electrical controls for the equipment. The assembly is mounted on adjustable feet. Water in the bath is heated by a cartridge element which is controlled by an adjustable on/off temperature controller connected to a PTC temperature sensor mounted in the wall of the bath. Temperature in the bath is also indicated on a glass thermometer mounted in a gland on the top of the bath. The temperature control system is switched on by operating the lefthand switch. A float switch in the bath disconnects the electrical supply to the cartridge element if the water level is too low. Page - 21
The capillary tube for the diffusion experiments is mounted in a gland on top of the bath. Air is supplied to the capillary tube via a flexible tube connected to the air pump. The air pump is switched on by operating the right-hand mains switch. The height of the liquid in the capillary tube is monitored using a travelling microscope mounted on a removable support stand which incorporates a Vernier height gauge. The water bath is fitted with a lever operated cock to facilitate draining using a piece of flexible tubing. The equipment is connected to the electrical supply using the integral cable. An earth leakage circuit breaker (RCCB) is installed at the right-hand end of the equipment to protect the user in the event of an electrical fault. The electrical components are protected by a mains fuse mounted at the rear of the equipment.
NOTE: The water bath will be damaged if the water temperature exceeds 80oC. Ensure that the temperature controller is not set above 60oC in use.
Page - 22
COMMISSIONING Fill the water bath with clean water to approximately 25mm from the top of the bath. Insert the microscope into the holder on the support stand and clamp by tightening the finger screw. Ensure that the eyepiece is fitted to the microscope. Loosen the rear gland on top of the water bath and carefully insert the glass thermometer. Tighten the gland to retain the glass thermometer but do not-overtighten. Do not fit the fragile capillary tube at this stage as it will be necessary to clean the tube then fill it with acetone before use. When installed, the capillary is inserted in the gland located at the front on top of the water bath. Do not over-tighten the gland. Connect the mains cable to the electrical supply ensuring that the voltage of the supply is correct to suit the equipment. Switch on the Earth Leakage Circuit Breaker (ELCB) at the right-hand end of the equipment by pressing the white lever towards the black test button. Press the black test button and observe that the white lever disengages. Reset the white lever to the “on” position. NOTE: If the ELCB does not trip when the black test button is depressed DO NOT USE THE EQUIPMENT. The ELCB must be checked by a competent electrician before the equipment is used. Operate the heater switch and set the temperature controller to 50oC. The temperature controller usually indicates the current temperature of water in the bath. To display the current set point of the controller, press the set point membrane key pad (top left). To change the set point, press the increase (˄) or decrease (˅) key, as required, while pressing the set point key. To avoid damage to the equipment do not set the temperature controller above 60oC. Check that the water heats to 50oC and remains at constant temperature (±1oC). Operate the air pump switch. Check that a stream of air is delivered at one end of the flexible tubing. The stream of air is only low velocity a may be detected by placing the end of the flexible tube against the cheek.
Page - 23
Instruction Manual
ION EXCHANGE APPARATUS
Page - 24
INTRODUCTION Ion Exchange is a natural process in which ions held on the surface of a solid displace other ions, of similar and equivalent electrical charge, from a solution in contact with the solid. The displaced ions become attached (i.e. held by electrostatic attraction) to the surface, while those originally on the surface go into solution. This process of exchange continues until the relative concentration of the two types of ions, on the surface and in solution, reach an equilibrium. The process is reversible, the direction of the exchange depending upon these relative concentrations. The simplest example of practical ion exchange is in the softening of water, when Ca2+ ions in the water (causing hardness) are exchanged for Na+ ions on the exchange material. When equilibrium is reached, i.e. when the exchange capacity of the material is exhausted, it can be regenerated by applying a concentrated solution of a sodium salt, usually sodium chloride, to restore Na+ ions on the surface. By the use of suitable ion exchange materials in two or more stages it is possible to remove all dissolved salts from solution – the process of demineralization. The ion exchange apparatus described in this manual enables both softening and demineralization to be studied. Besides these uses in the treatment of water supplies, ion exchange processes are also widely employed in industry.
Page - 25
DIAGRAM
Page - 26
DESCRIPTION Parts of Equipment 1) Two Vertical Columns 2) Manifolds at the top. 3) Manifolds at the bottom. 4) Tank 5) Pump 6) Flowmeter 7) Sliding Tube Arrangement 8) Controlled Valves 9) Conductivity Meter 10) Cell 11) Backboard 12) Joint
Brief Description The apparatus, which is designed for experiments on both water softening and demineralization, consists of two vertical columns of 15mm internal diameter, mounted on a backboard containing respectively a cation exchange and an anion exchange resin. Manifolds at the top and bottom of the columns are fitted with valves which allow flow to be controlled through on or both columns, in an upward or downward direction. The liquids to be passed through the columns are stored in the tank to the left of the apparatus and applied via the pump and flowmeter. The liquids are selected by lifting and trans versing the sliding tube arrangement at the front of the tank. After passing through the columns they may be collected for analysis by way of lengths of tubing attached to the nozzle equipment includes a conductivity meter connected to a cell on the outlet line to monitor the demineralized water. The various processes to be used in the experiments are as follows: a. Water to be softened, which will pass downwards through the cation exchanger only. Page - 27
b. Water to be demineralized, which will pass downwards through the cation exchanger and then upward through the anion exchanger. c. Regenerated solutions (followed by distilled or demineralized water for flushing), which are stored in separate tanks, and will pass downwards through either the cation or the anion exchange column. d. Water (preferably distilled or demineralized) which will pass upwards through either column to flush out any sediment and to release any air trapped in the resin.
Page - 28
CONNECTION TO SERVICES ELECTRICAL SUPPLY FOR VERSION W 9-A: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 20-240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 25 AMP
ELECTRICAL SUPPLY FOR VERSION W9-B:
The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 0.5 AMP
Page - 29
COMMISSIONING For initial testing fill all four tanks with ordinary tap water. 1. Place backboard and tank on a firm level surface. 2. Fill tanks with ordinary tap water (1 liter approximately). 3. Connect pump supply tube to flowmeter nozzle, and effluent return tubes to sump tank nozzle. 4. Lift selector tube and traverse along to each compartment. 5. Connect to electrical supply. 6. Check all pipe connections are secure and all valves are closed. 7. Set flowmeter to mid-position. 8. Select tank C, open valves 3 and 6. Switch on pump and check that water returns to sump tank. Close valves. 9. Open valves 2 and 12 and check that water returns to sump tank. Close valves. 10. Open valves 2 and 10. A container will be required to catch the water (sample) from valve 10. Close valves. 11. Open valves 3 and 9, check that water returns to sump tank. Close valves. 12. Open valves 1 and 15, check that water returns to sump tank. Close valves. 13. Open valves 2, 13 and 15, check that water returns to sump tank. Close valves. 14. Open valves 2, 13 and 16. A container will be required to catch the water (sample) from valve 16. Close valves. 15. Open drainage valve on sump tank, ensure it operates correctly. 16. Switch on conductivity meter, check that it operates correctly. 17. Wait 10 minutes and check for leaks at base of sump tank.
Page - 30
OPERATION OF CONDUCTIVITY METER The conductivity meter is supplied attached to the backboard of the W9. It is powered by a 9 Volt power supply which plugs into a 3-pin socket situated at the rear of the backboard. This supplies power to the meter via a jack plug plugged into the top of the unit. Connections for the conductivity probe run up the side of the W9. The 2 black banana plugs are plugged into the left-hand set of banana sockets. To operate the conductivity meter, switch the left-hand switch to [XI]. Switch the right-hand switch to [x10-2] (fully anti-clockwise) and increase the sensitivity of the meter by switching clockwise until a reading is obtained. Multiply the reading by the switch positions indication which will produce the correct conductivity of the solution.
Page - 31
Instruction Manual
BATCH DISTILLATION APPARATUS
Page - 32
INTRODUCTION Distillation has always been and will continue to be one of the most important industrial processes for separating the different components of a liquid mixture. Laboratory scale distillation columns are needed to provide adequate practical training for student engineers and plant operators in a safe environment. They may also be used to acquire process separation data, of use in full-scale plant design. Traditionally, large scale "pilot plant" has been used for this purpose and that has presented problems particularly those of large volumes of chemicals required and long time periods to reach equilibrium. Also, restrictions in the chemicals used due to their inflammable nature have limited the use of the equipment. The batch distillation column has been developed specifically to overcome these main disadvantages and present training equipment which is both economical and safe to use. Almost all of the well documented binary mixtures are flammable and this has dictated the design of the electrical equipment used. The flameproof electrical equipment specification used complies with relevant British Standards for equipment being used in a Zone 1 area. This is the area within the framework of the process where "an explosive gas – air mixture is likely to occur in normal operation". An area extending for 2m around and above the equipment is a Zone 2 area where no non-flameproof electrical equipment can be used and the control console is attached to the process by a suitable length of cable to allow it to be positioned outside this area. A variety of batch distillation experiments can be carried out using packed or sieve plate columns and the process can be operated at atmospheric pressure or under vacuum.
Page - 33
DIAGRAMS
Page - 34
Page - 35
Page - 36
DESCRIPTION Parts of Equipment 1) Steel Framework 2) Adjustable Feet 3) Glass Section-1 4) Glass Section-2 5) Condenser 6) Top Product Tank 7) Decanter Vessel 8) Reflux Ratio Control Valve 9) Reboiler 10) Level Sensor 11) Sight Glass 12) Vacuum Pump 13) Filler Plug 14) Hose Nozzle 15) Vacuum Pump 16) Overflow 17) Underflow
Nomenclature V1 to V15
=
Valves
T1 to T13
=
Thermocouples
P1
=
Pressure Gauge
D
=
Plate
E
=
Central Support Rod
F
=
Weir
G
=
Downcomer
H
=
U-Tube
PRV1
=
Pressure Relief Valve
FI1
=
Rotameter
Page - 37
Brief Description The equipment is mounted on a floor standing, welded tubular steel framework fitted with four adjustable feet. The frame is designed to allow the use of a fork lift or pallet truck to maneuver the unit into position initially. The equipment comprises a 50mm diameter sieve plate column made up of two glass sections each containing four sieve plates. The columns are separated by a central feed section and arranged vertically for counter-current vapor / liquid flow. Also, installed within the framework are: Reboiler, condenser, top product lank, decanter, reflux valve, vacuum pump and all appropriate instrumentation. The reboiler situated at the base of the column is manufactured from 316 stainless steel and incorporates a flameproof immersion type heating element. For batch operation, valve (V1) remains closed so that the reboiler can be filled with the initial charge (10 to 12 liters) of binary mixture. Valve (V1) must remain closed at all times as it is only used on the continuous feed version of this equipment. The column and reboiler are both insulated to minimize heat loss. A level sensor inside the reboiler protects the heating element from overheating due to low operating level and a sight glass allows the level in the reboiler to be observed. The glass column incorporates a total of eight sieve plates in two sections each containing four plates. Each plate (D) is located by a central support rod (E) and incorporates a weir (F) and downcomer (G) to create a liquid seal between successive stages. The liquid seal on the final plate in each section is achieved by U-tube (H). Vapor from the top of the column passes to a water-cooled, coil-in-shell condenser which can be insulated to allow heat balances to be carried out. (The insulated jacket should not be fitted to the condenser for normal operation.) The shell of the condenser incorporates a pressure relief valve (PRV1) to protect the system in the event of a blocked vent and cooling water failure. Cooling water enters the condenser at a regulated rate through a rotameter (FI1) and the flowrate is controlled by diaphragm valve (V5). A cooling water supply is connected to the inlet nozzle and serves also to operate the vacuum pump when operation at reduced pressure is required. Water supply to the vacuum pump is controlled by valve (V14). Condensate is collected in a glass decanter (phase separator) which is by-passed for normal distillation experiments by opening valve (V10). When the decanter is in use Page - 38
(separation of two immiscible liquids as condensate), valve (V10) is closed so that the overflow and underflow pipes inside the vessel, can take effect. With valve (V10) open, condensate from the condenser outlet passes directly through the decanter to the inlet of the reflux ratio control valve which is a 3-way solenoid operated valve. Depending on the setting of the reflux timers, condensate is directed by the reflux valve either back to the top of the column or to the top product collecting vessel. When directed to the column, the reflux passes through a U-seal where a valve (V3) can be used for measuring boil-up rate or for draining the U-seal. The contents of the top product tank can be drained into the reboiler for re-use via valve (V12). Temperatures within the system are monitored by thirteen thermocouple sensors (T1 to T13) located at strategic positions in the system. T1 to T8 are located in the column and measure, the temperature of the liquid on each sieve plate. The total pressure drop across the column is indicated on a U-tube manometer (deltaP1) via appropriate tapings in the column fitted with isolating valves (V6) and (V7). All of the vessels in the system are connected to a common vent on the top product receiver. This vent is normally connected through a 4.0m length of tubing to a fume cupboard or safe atmospheric vent outlet. Operation at reduced system pressures is achieved using the water powered vacuum pump. When in use, the flexible vent pipe from the common connection on the top product receiver is attached to the inlet of this vacuum pump at, and motive water admitted via valve (V14). The level of vacuum is adjusted using needle valve (V15) and is indicated on pressure gauge (P1).
Control Console The individual sections of the console are described in this article on the next page. The console is attached to the process unit by an umbilical cable which is of adequate length to allow the console to be positioned at least 2.0m away (outside the "Zone 2" area).
Page - 39
Page - 40
Page - 41
Page - 42
CONNECTION TO SERVICES ELECTRICAL SUPPLY FOR VERSION-A: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 220-240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 10 AMP
ELECTRICAL SUPPLY FOR VERSION-B: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 20 AMP
Page - 43
COMMISSIONING The following procedure is intended as a series of checks to ensure that the equipment is operating correctly. Water is used in place of organic solvents for safety purposes. 1. Switch on electrical power to the control console. This is achieved by moving the ELCB switch to the UP position. The LOW-LEVEL lamp in the reboiler heater section of the console will be illuminated. The reboiler power, reflux timer, column temperature and process temperature digital display will also be illuminated. 2. Ensure that all valves (V1 to V15) are in the closed position. Valves included are V1, V2, V3, V4, V5, V6, V7, V10, Vl2, V14 and V15. For normal operation ensure that the insulated jacket has been removed from the shell of the condenser. 3. Remove the filler plug from the top of the reboiler and, using a suitable funnel, fill the reboiler with 10 liters of water. The LOW-LEVEL lamp will go out. The reboiler level switch operation should be tested by draining water from the reboiler using drain valve (V2) and refilling through the filler cap. 4. Turn on laboratory cold water supply. Open flow control valve (V5) to give maximum flow into the condenser via flowmeter (FI1). Check for leaks. 5. To prime the U-lube manometer (deltaP1), disconnect the black Viton tubing at the valves (V6) and (V7). Using a suitable syringe filled with clean water, inject the water into the manometer. It is advisable to hold one end of the Viton tubing of valve (V7) vertically, insert the syringe and very slowly inject the water so that it flows down the inside wall of the tube. This will prevent slugs of water causing air locks in the tube. Fill the manometer tube until an equal level is visible about halfway up the scale, close valves (V6) and (V7). 6. Switch on reboiler heater power at the console and adjust power to the heater to 1.50 kW. The water in the reboiler will begin to heat up and this can be observed by selecting (T9) on the process temperature digital display. 7. As the water begins to boil, vapor will rise up the distillation column and this can be observed on the top plate of each of the two column sections as the insulation has been cut away in this area for this purpose. Turn the heater power down to 1.00 kW. Eventually vapor will reach the condenser and drops of condensate will be observed entering the glass decanter vessel. Allow water condensate to build up in the
Page - 44
decanter vessel until it reaches the adjustable overflow and observe the condensate overflowing to the top product receiver vessel. 8. The reflux valve, when in the de-energized state (reflux control switch on the console is in the OFF position), will direct all condensate back to the top of the column as reflux. Open valve (V10) at the base of the decanter and observe condensate flowing to the top of the column via the reflux valve. When a proportion of the condensate is required to be directed to the top product receiver vessel, it is necessary to set the reflux timer to give the ratio required. Set the timer to give 4 sec. to both column and receiver. This is achieved by first pressing the SET button on the reflux timer three times. The flashing digits are adjusted in turn using the (delta) button. The CY- and CY+ digits in the bottom right of the display indicate flow of condensate back to the column and to the top product tank respectively. Switch on the reflux control at the console. Observe condensate being directed to the column and receiver for the set time periods. 9. Observe the flows and temperatures for several minutes and allow the equipment to establish an equilibrium condition making slight adjustments where necessary. Ensure that all thermocouple sensors are giving sensible readings on the digital display at the console. In normal operation ensure that the power to the reboiler is not too high and the flow of cooling water is sufficient to prevent loss of vapor through the vent system (by overloading the condenser). 10. Open V6, and V7 and observing the pressure difference in the manometer. Close V6 and V7. 11. Open valve V14, allowing water to flow to the vacuum pump. After a few minutes, observe on gauge P1 the pressure in the system begin to fall. Check for leaks. Even a very small leak of air into the system will affect the achievable vacuum. Allow the vacuum to reach a level of 200 mbar (-0.8 bar on P1). This should be achievable in 30-40 minutes from the time of opening V14. Close V14 and ensure that the nonreturn valve in the vacuum pump stops ingress of air and water. Break the vacuum by opening slowly, valve V15. 12. The equipment can now be shut down and allowed to cool. Switch off heater power and reflux valve at the console. Drain all of the water from the system using the drain valves V2, V3, V4. It is important that all water be removed from the system as the presence of water with a mixture of solvents will adversely affect the experiments.
Page - 45
OPERATIONAL PROCEDURES a) Reflux Ratio Control The reflux ratio timer on the control console is used to set the quantity and frequency of condensate returning to the distillation column. With the timer switched off, all of the condensate will be directed to the column (total reflux). Example of Setting the Timer: If the reflux ratio required is 2:1 and the total cycle required is 9 seconds: This means that condensate will be directed by the reflux ratio valve to the column for 6 seconds, then to the top product receiver for 3 seconds. This cycle will then be repeated continuously until different values are inserted to the controller or until the reflux control is switched off. If a ratio of 4:1 is required over the same cycle time: Condensate will be directed to the column for 7.2 seconds and to the top product receiver for 1.8 seconds. 4 + 1 = 5; 9/5 = 1.8; 4 x 1.8 = 7.2 To set the controller: This is achieved by first pressing the SET button on the reflux timer three times. The flashing digits are adjusted in turn using the (delta) button. The CY- and CY+ digits in the bottom right of the display indicate flow of condensate back to the column and to the top product tank respectively.
b) Pressure Drop in Column The overall pressure drop over the column can be measured using the manometer delta P1. Always open V6 before V7, take the pressure reading then immediately close both valves. This will reduce the risk of contamination of the manometer water by the hydrocarbons. Also, to prevent contamination, never open valves V6 or V7 when flooding is occurring on the sieve plates (boil-up rate too high).
Page - 46
c) Sampling Valves Samples for analysis can be taken from pertinent points in the system as follows: Liquid in reboiler
- V2 take care, liquid at boiling point
Condensate from condenser - V3 (reflux/ top product) Top product receiver
- V4
Note: When using valve V3 to obtain a sample of top product or to measure boil up rate the valve should not be fully opened to. prevent vapor from escaping. Gradually open valve V3 until flow of reflux into the column stops but liquid is retained in the flexible connecting pipe. Small adjustments of the valve position can be applied to maintain the desired level in the pipe. Provided that the same level in the pipe is maintained at the start and finish of the timing operation then the boil up rate measured will be accurate.
d) Suitability of Test Mixtures The following binary mixtures have been selected as the most suitable for use with the distillation column. Methylcyclohexane / Toluene Toluene / Chlorobenzene Cyclohexane / n-Heptane Methanol / Water Chlorobenzene / Ethylbenzene Methanol / Ethanol Ethanol / Water Boiling Point oC Flash Point oC Ignition Temperature oC Toluene 111 6 535 Ethanol 78 12 425 Cyclohexane 81 -18 259 Methylcyclohexane 101 -4 260 Chlorobenzene 132 28 637 n-Heptane 98 -4 215 Methanol 65 11 455 Ethylbenzene 136 15 431
Page - 47
Many other liquids can be used but the information above is required to ensure that their characteristics are within the flameproof specification of the equipment.
e) Operation of the Decanter (Phase Separator) The decanter in normal operation is used with valve (VI0) open which allows condensate entering the vessel to flow directly to the reflux valve.
When carrying out an experiment which utilizes a third liquid component, valve (V10) is closed and the decanter comes into operation. The condensate entering the decanter will be made up of the miscible binary mixture plus an immiscible component. The heavier component will separate and collect at the base of the decanter and its' level will begin to rise. Eventually the lighter phase will overflow the fixed overflow and, when the level is sufficiently high, the heavier phase will overflow the adjustable overflow. The adjustable overflow will always be below the level of the fixed overflow and when adjusted will determine the height of the interface between the light and heavy components.
Page - 48
f) Reboiler Heating of the liquid in the reboiler is achieved by an electrical heating element. The maximum power of the element is 2.0 kW and this is adjustable at the control console. Due to the various flux requirements of the liquids which can be used in the reboiler, the heater must always be switched on at zero power (adjustment fully anticlockwise). The power can then be increased carefully until boiling is achieved and fine adjustment is carried out to cause the required activity on the sieve plates (observed on Trays 1 and 5). Excessive power to the reboiler may cause vapor to escape from the vent pipe due to overloading of the condenser. NOTE: The reboiler heater maximum power is 2.0 kW rated at a supply voltage of 240V (120V). 2.0 kW will not be achieved if the supply voltage is low but this will not affect the process as maximum power is rarely, if ever, required.
Page - 49
Instruction Manual
CONTINUOUS DISTILLATION APPARATUS
Page - 50
INTRODUCTION Distillation has always been and will continue to be one of the most important industrial processes for separating the different components of a liquid mixture. Laboratory scale distillation columns are needed to provide adequate practical training for student engineers and plant operators in a safe environment. They may also be used to acquire process separation data, of use in full-scale plant design. Considerable advances in the instrumentation and control of distillation columns have been made in recent years, prompted by the advent of computer-linked systems supported by software packages for handling plant operating data. There- is a consequent need for state-ofthe-art training and project equipment which reflects these advances. The range is based on a common distillation column arrangement, which uses flameproof components throughout. Depending on the options selected, the following distillation processes may be demonstrated and form student practical assignments: 1. Batch or continuous operation 2. Packed or plate column operation 3. Vacuum distillation 4. Azeotropic or extractive distillation 5. Alternative feed tray locations 6. Varying the feed temperature. An important new feature is incorporated within the plate column, whereby the temperature on each sieve tray is measured and displayed. The Continuous Distillation Column incorporates an electrical console which provides access to the various signals associated with measurement and control of the process allowing a variety of control possibilities: 1. Manual operation 2. Data logging using PC or chart recorder 3. Manual control via an operator VDU using a mimic diagram 4. Direct digital control using PC 5. Use of industrial PID or programmable controllers 6. Use of customer-provided controllers
Page - 51
DIAGRAMS
Page - 52
Page - 53
Page - 54
DESCRIPTION Parts of Equipment 1) Tubular Steel Framework 2) Four Adjustable Feet 3) Glass Section 4) Glass Section 5) Feed Tank 6) Feed Tank 7) Peristaltic Type Feed Pump 8) Condenser 9) Bottom Product Tank 10) Top Product Tank 11) Decanter 12) Reflux Valve 13) Reboiler 14) Union 15) Bottom Product Cooler 16) Compression Union 17) Level Sensor 18) Sight Glass 19) Inlet Nozzle 20) Vacuum Pump 21) Filler Plug 22) Hose Nozzle 23) Vacuum Pump 24) Azeotropic Dosing Vessel 25) Overflow 26) Underflow
Page - 55
Nomenclature
V1 to V15 = Valves T1 to T14
= Thermocouple Sensors
PRV1
= Pressure Relief Valve
FI1
= Rotameter
Delta P1
= U-Tube Manometer
A
= Base Connection
B
= Centre Connection
C
= Top Connection
D
= Plate
E
= Central Support Rod
F
= Weir
G
= Downcomer
H
= U-Tube
Brief Description The equipment is mounted on a floor standing, welded tubular steel framework fitted with four adjustable feel. The frame is designed to allow the use of a fork lift or pallet truck to maneuver the unit into position initially. The equipment comprises a 50mm diameter sieve plate column made up of two glass sections and each containing four sieve plates. The columns are separated by a central feed section and arranged vertically for countercurrent vapor / liquid flow. Also, installed within the framework are: reboiler, two 5-liter feed tanks and, a peristaltic type feed pump, condenser, bottom and top product tanks, decanter, reflux valve, azeotropic dosing vessel, vacuum pump and all appropriate instrumentation. The reboiler situated at the base of the column is manufactured from 316 stainless steel and incorporates a flameproof immersion type heating element Either batch or continuous distillation can be carried out using this reboiler.
Page - 56
In continuous operation, valve (V1) is open and bottom product flows from the reboiler through the bottom product cooler to the bottom product tank. It is possible to preheat the feed to the column by directing the feed through a spiral coil in the bottom product cooler where heat is transferred from product leaving the reboiler at the boiling point. When feeding cold feed directly to the column, the product from the reboiler is cooled in the bottom product cooler by circulating cold water through the spiral coil. For batch operation, valve (V1) remains closed so that the reboiler can be filled with the initial charge (10 to 12 liters) of binary mixture. The column and reboiler are both insulated to minimize heat loss. A level sensor inside the reboiler protects the heating element from overheating due to low operating level and a sight glass allows the level in the reboiler to be observed. Feed mixture from either of the feed tanks is pumped by pump to the base, center or top of the distillation column at connections (A), (B) or (C) respectively. The feed pump incorporates a length of Viton rubber tubing. This tubing is suitable for all of the recommended test mixtures. Where other test mixtures are being used, the suitability of this material must be checked. The glass column incorporates a total of eight sieve plates in two sections and each containing four plates. Each plate (D) is located by a central support rod (E) and incorporates a weir (F) and downcomer (C) to create a liquid seal between successive stages. The liquid seal on the final plate in each section is achieved by U-tube (H). Vapor from the top of the column passes to a water-cooled, coil-in-shell condenser which can be insulated to allow heat balances to be carried out. (The insulated jacket should not be fitted to the condenser for normal operation.) The shell of the condenser incorporates a pressure relief valve to protect the system in the event of a blocked vent and cooling water failure. Cooling water enters the condenser at a regulated rate through a rotameter and the flowrate is controlled by diaphragm valve (V5). A cooling water supply is connected to the inlet nozzle and serves also to operate the vacuum pump when operation at reduced pressure is required. Water supply to the vacuum pump is controlled by valve. Condensate is collected in a glass-decanter (VI ) (phase separator) which is bypassed for normal distillation experiments by opening valve. When the decanter is in use (demonstration of azeotropic distillation), valve (V10) is closed so that the overflow and underflow pipes inside the vessel, can take effect. With valve (V10) open, condensate from the Page - 57
condenser outlet passes directly through the decanter to the inlet of the reflux ratio control valve which is a 3-way solenoid operated valve. Depending on the setting of the reflux timers, condensate is directed by the reflux valve either back to the top of the column or to the top product collecting vessel. When directed to the column, the reflux passes through a U-seal where a valve (V3) can be used for measuring boil-up rate or for draining the U-seal. The contents of the top product tank can be drained into the reboiler for re-use via valve (V12). Temperatures within the system are monitored by fourteen thermocouple sensors (T1 to T14) located at strategic positions in the system. T1 to T8 are located in the column and measure the temperature of the liquid on each sieve plate. There are seventeen locations for the temperature sensors, three of which do not have sensors installed but which can be fitted with sensors moved from other, less relevant locations when necessary. The total pressure drop across the column is indicated on a U-tube manometer (API) via appropriate tapings in the column fitted with isolating valves (V6) and (V7). All of the vessels in the system are connected to a common vent on the top product receiver. This vent is normally connected through a 4.0m length of tubing to a fume cupboard or safe atmospheric vent outlet. Operation at reduced system pressures is achieved using the water powered vacuum pump. When in use, the flexible vent pipe from the common connection on the top product receiver is attached to the inlet of this vacuum pump, and motive water admitted via valve (V14). The level of vacuum is adjusted using needle valve (V15) and is indicated on pressure gauge (P1). A packed column is supplied loose. This column can be fitted in place of the sieve plate column where it is required to demonstrate the characteristics of a packed column.
Control Console The console is attached to the process unit by an umbilical cable which is of adequate length to allow the console to be positioned at least 2.0m away (outside the "Zone 2" area). The lower part of the console (beneath the control sections) contains the Zener diode barriers which provide intrinsic safety to the thermocouple sensors and the level switch in the reboiler.
Page - 58
Page - 59
Page - 60
Page - 61
Page - 62
CONNECTION TO SERVICES ELECTRICAL SUPPLY FOR VERSION-A: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 220-240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 10 AMP
ELECTRICAL SUPPLY FOR VERSION-B: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 20 AMP
Page - 63
COMMISSIONING The following procedure is intended as a series of checks to ensure that the equipment is operating correctly. Water is used in place of organic solvents for safety purposes. 1. Switch on electrical power to the control console. This is achieved by moving the ELCB switch to the UP position. The LOW-LEVEL lamp in the reboiler heater section of the console will be illuminated. The reboiler power, reflux timer, column temperature and process temperature digital display will also be illuminated. 2. Ensure that all valves (V1 to V15) are in the closed position. Valves included are V1, V2, V3, V4, V5, V6, V7, V10, Vl2, V14 and V15. For normal operation ensure that the insulated jacket has been removed from the shell of the condenser. 3. Remove the filler plug from the top of the reboiler and, using a suitable funnel, fill the reboiler with 10 liters of water. The LOW-LEVEL lamp will go out. The reboiler level switch operation should be tested by draining water from the reboiler using drain valve (V2) and refilling through the filler cap. 4. Open valve (V1) and observe water flowing from the reboiler through valve (V1) and through the bottom product cooler to the bottom product receiver. Water will continue to flow until it reaches the overflow level in the reboiler. The LOW-LEVEL lamp should not come back on. Close (V1) and replenish the reboiler with 6.0 liters of water. 5. Fill the feed tanks with clean water (approximately 4 liters in each). 6. Turn on laboratory cold water supply. Open flow control valve (V5) to give maximum flow into the condenser via flowmeter (FI1). Check for leaks. 7. To prime the U-lube manometer (deltaP1), disconnect the black Viton tubing at the valves (V6) and (V7). Using a suitable syringe filled with clean water, inject the water into the manometer. It is advisable to hold one end of the Viton tubing of valve (V7) vertically, insert the syringe and very slowly inject the water so that it flows down the inside wall of the tube. This will prevent slugs of water causing air locks in the tube. Fill the manometer tube until an equal level is visible about halfway up the scale, close valves (V6) and (V7). 8. Switch on reboiler heater power at the console and adjust power to the heater to 1.50 kW. The water in the reboiler will begin to heat up and this can be observed by selecting (T9) on the process temperature digital display.
Page - 64
9. As the water begins to boil, vapor will rise up the distillation column and this can be observed on the top plate of each of the two column sections as the insulation has been cut away in this area for this purpose. Turn the heater power down to 1.00 kW. Eventually vapor will reach the condenser and drops of condensate will be observed entering the glass decanter vessel. Allow water condensate to build up in the decanter vessel until it reaches the adjustable overflow and observe the condensate overflowing to the top product receiver vessel. 10. The reflux valve, when in the de-energized state (reflux control switch on the console is in the OFF position), will direct all condensate back to the top of the column as reflux. Open valve (V10) at the base of the decanter and observe condensate flowing to the top of the column via the reflux valve. When a proportion of the condensate is required to be directed to the top product receiver vessel, it is necessary to set the reflux timer to give the ratio required. Set the timer to give 4 sec. to both column and receiver. This is achieved by first pressing the SET button on the reflux timer three times. The flashing digits are adjusted in turn using the (delta) button. The CY- and CY+ digits in the bottom right of the display indicate flow of condensate back to the column and to the top product tank respectively. Switch on the reflux control at the console. Observe condensate being directed to the column and receiver for the set time periods. 11. Start the feed pump at the console after first ensuring the speed control is set to minimum. Gradually increase the speed of the pump to graduation 4 on the dial indicator. The pump will require calibration but, as a guide, the variable speed control of the motor speed will give flows of 0 to 270 ml/min corresponding to 0 to 10 on the dial control. Water will begin to flow from the feed tank to the column. The feed to the column is set initially at the column mid-point. There are connections also for the feed at the top and base of the column and feed can be directed to any of the eight sieve plates if required by removing a thermocouple and replacing with the feed pipe. 12. Observe the flows and temperatures for several minutes and allow the equipment to establish an equilibrium condition making slight adjustments where necessary. Ensure that all thermocouple sensors are giving sensible readings on the digital display at the console. Whenever the flow rate of reflux or feed needs to be altered, only very small increments must be used in order not to unbalance the system. In normal operation ensure that the power to the reboiler is not too high and the flow of cooling water is sufficient to prevent loss of vapor through the vent system (by overloading the condenser). Page - 65
13. Open V6, and V7 and observing the pressure difference in the manometer. Close V6 and V7. 14. Open valve V14, allowing water to flow to the vacuum pump. After a few minutes, observe on gauge P1 the pressure in the system begin to fall. Check for leaks. Even a very small leak of air into the system will affect the achievable vacuum. Allow the vacuum to reach a level of 200 mbar (-0.8 bar on P1). This should be achievable in 30-40 minutes from the time of opening V14. Close V14 and ensure that the nonreturn valve in the vacuum pump stops ingress of air and water. Break the vacuum by opening slowly, valve V15. 15. The equipment can now be shut down and allowed to cool. Switch off heater power, feed pump motor and reflux valve at the console. Drain all of the water from the system using the drain valves V2, V3, V4, VI1 and by breaking the pipe connections of the bottom product cooler (15) and the feed pump (7). It is important that all water be removed from the system as the presence of water with a mixture of solvents will adversely affect the experiments.
Page - 66
OPERATIONAL PROCEDURES a) Reflux Ratio Control The reflux ratio timer on the control console is used to set the quantity and frequency of condensate returning to the distillation column. With the timer switched off, all of the condensate will be directed to the column (total reflux). Example of Setting the Timer: If the reflux ratio required is 2:1 and the total cycle required is 9 seconds: This means that condensate will be directed by the reflux ratio valve to the column for 6 seconds, then to the top product receiver for 3 seconds. This cycle will then be repeated continuously until different values are inserted to the controller or until the reflux control is switched off. If a ratio of 4:1 is required over the same cycle time: Condensate will be directed to the column for 7.2 seconds and to the top product receiver for 1.8 seconds. 4 + 1 = 5; 9/5 = 1.8; 4 x 1.8 = 7.2 To set the controller: This is achieved by first pressing the SET button on the reflux timer three times. The flashing digits are adjusted in turn using the (delta) button. The CY- and CY+ digits in the bottom right of the display indicate flow of condensate back to the column and to the top product tank respectively.
b) Pressure Drop in Column The overall pressure drop over the column can be measured using the manometer delta P1. Always open V6 before V7, take the pressure reading then immediately close both valves. This will reduce the risk of contamination of the manometer water by the hydrocarbons. Also, to prevent contamination, never open valves V6 or V7 when flooding is occurring on the sieve plates (boil-up rate too high).
Page - 67
c) Sampling Valves Samples for analysis can be taken from pertinent points in the system as follows: Feed Liquid
- From feed tank
Liquid in reboiler
- V2 take care, liquid at boiling point
Condensate from condenser - V3 (reflux/ top product) Top product receiver
- V4
Bottom product receiver
- V11
Note: When using valve V3 to obtain a sample of top product or to measure boil up rate the valve should not be fully opened to. prevent vapor from escaping. Gradually open valve V3 until flow of reflux into the column stops but liquid is retained in the flexible connecting pipe. Small adjustments of the valve position can be applied to maintain the desired level in the pipe. Provided that the same level in the pipe is maintained at the start and finish of the timing operation then the boil up rate measured will be accurate.
d) Suitability of Test Mixtures The following binary mixtures have been selected as the most suitable for use with the distillation column. Methylcyclohexane / Toluene Toluene / Chlorobenzene Cyclohexane / n-Heptane Methanol / Water Chlorobenzene / Ethylbenzene Methanol / Ethanol Ethanol / Water Boiling Point oC Flash Point oC Ignition Temperature oC Toluene 111 6 535 Ethanol 78 12 425 Cyclohexane 81 -18 259 Methylcyclohexane 101 -4 260 Chlorobenzene 132 28 637 n-Heptane 98 -4 215 Page - 68
Methanol Ethylbenzene
65 136
11 15
455 431
Many other liquids can be used but the information above is required to ensure that their characteristics are within the flameproof specification of the equipment.
e) Operation of the Decanter (Phase Separator) The decanter in normal operation is used with valve (VI0) open which allows condensate entering the vessel to flow directly to the reflux valve.
When carrying out an experiment which utilizes a third liquid component, valve (V10) is closed and the decanter comes into operation. The condensate entering the decanter will be made up of the miscible binary mixture plus an immiscible component. The heavier component will separate and collect at the base of the decanter and its' level will begin to rise. Eventually the lighter phase will overflow the fixed overflow and, when the level is sufficiently high, the heavier phase will overflow the adjustable overflow. The adjustable overflow will always be below the level of the fixed overflow and when adjusted will determine the height of the interface between the light and heavy components.
Page - 69
f) Reboiler Heating of the liquid in the reboiler is achieved by an electrical heating element. The maximum power of the element is 2.0 kW and this is adjustable at the control console. Due to the various flux requirements of the liquids which can be used in the reboiler, the heater must always be switched on at zero power (adjustment fully anticlockwise). The power can then be increased carefully until boiling is achieved and fine adjustment is carried out to cause the required activity on the sieve plates (observed on Trays 1 and 5). Excessive power to the reboiler may cause vapor to escape from the vent pipe due to overloading of the condenser. NOTE: The reboiler heater maximum power is 2.0 kW rated at a supply voltage of 240V (120V). 2.0 kW will not be achieved if the supply voltage is low but this will not affect the process as maximum power is rarely, if ever, required.
Page - 70
Instruction Manual
GAS ABSORPTION COLUMN APPARATUS
Page - 71
INTRODUCTION The packed tower, in which two fluids flowing in opposite directions enable a chemical component to be transferred from one fluid phase to the other, occurs in almost all chemical plants. The process may be gas absorption, distillation, solvent extraction or chemical reaction. A knowledge of the characteristics of both fluid flow and of mass transfer in such towers is necessary for both plant operators and designers. The Gas Absorption Apparatus has been designed to allow these studies to be made, and the instrumentation and layout enables students to follow both the hydrodynamic characteristics in the absence of mass transfer, and also, separately, to advise the performance of the mass transfer process involved in gas absorption. The size of the equipment has been chosen so that experiments may be completed in a typical laboratory class period, while at the same time being capable of demonstrating full scale plant behavior. Considerable attention is directed towards matters of safety which is of crucial importance in the process industries.
Page - 72
DIAGRAM
Page - 73
DESCRIPTION Parts of Equipment 1) Sump Tank 2) Valve in the Discharge Pipe 3) Mercury Manometers 4) Flowmeter 5) Hempl Gas Analysis Apparatus 6) Air Flow Control Valve 7) Gas Sampling Cock 8) Water Flow Control Valve 9) Flowmeter 10) Gas Flow Control Valve 11) Gas Sampling Cock 12) Air Compressor 13) Water Pump 14) Drain Cock 15) C2 Control Valve 16) C4 Outlet Valve
Brief Description The equipment consists of a 75mm diameter column in which there are two lengths of Raschig ring packing material. Pressure tapings are provided at the base, center and top of the column to determine pressure drops across the column. Sampling points are also provided for the gas at the same three points. The liquid outlet stream and feed solution are also equipped with sampling points. Suitable manometric measurement is included. Water is taken from a sump tank, and pumped to the column via a calibrated flowmeter. Gas is taken from a pressure cylinder through a calibrated flowmeter, and mixed with air supplied and monitored from a small compressor in a pre-determined (but variable) mixed ratio. The mixture is fed to the base of the tower in which a liquid seal is provided. The effluent gas leaves the top of the column and is intended to be exhausted to atmosphere outside the laboratory building. The apparatus
Page - 74
is designed to absorb carbon dioxide/air mixture into an aqueous solution flowing down the column. Gas analysis apparatus is provided for this system. Diluted ammonia may be used as alternative to carbon dioxide but this is not recommended unless safe operating/disposal procedures are adopted.
CONNECTION TO SERVICES STANDARD ELECTRICAL SUPPLY The equipment requires connection to a 0.6kW, single phase fused electrical supply. The standard electrical supply for this equipment is 220/240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 7 amp
NON-STANDARD ELECTRICAL SUPPLY When supplied for operation from a non-standard electrical supply (110/130V, 50/60Hz or 220V, 60Hz), the equipment incorporates a transformer of appropriate current rating. In this case the transformer is mounted behind the sump tank. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the transformer. Connection should be made as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 13 amp at 110/130 V 7 amp at 220V
Page - 75
COMMISSIONING 1. Fill sump tank with clean water. 2. Connect the electrical supply cable to the appropriate mains supply. 3. Prime the water and mercury manometers as appropriate. 4. Fill the Hempl gas analysis apparatus with water up to the '0' mark on the scale. 5. Connect a CO2 gas cylinder, fitted with a regulator, to the inlet regulator on the equipment with a flexible tube, and set the cylinder regulator to minimum pressure. 6. Open fully the gas flow control valve on the gas flowmeter (small, center flowmeter) and open the main gas cylinder valve. 7. Increase the cylinder regulator output pressure to give maximum flow on the gas flowmeter and dose the main cylinder valve. 8. Close the air and water flow control valves. Close the gas sampling cocks on the absorption column. Check that the valve in the discharge pipe into the sump tank is fully open. Switch on the water pump and check that water flow is obtained through the flowmeter and down the column on opening the control valve. 9. Switch on the air compressor and check that air flow is obtained through the flowmeter and up the column on opening the control valve. 10. Check that the manometers indicate the pressure drop across the column (connecting valves must be correctly set). (The water manometer range will cover all normal situations). 11. Check that the Hempl gas analysis apparatus operates correctly by following the instructions in the appropriate experiment sheet. 12. Close the flow control valves and switch off the pumps. 13. Drain the Hempl apparatus. 14. Drain the water seal with the small drain cock at the bottom of the “U” beneath the column. The equipment is now ready for use.
Page - 76
Instruction Manual
LIQUID-LIQUID EXTRACTION APPARATUS
Page - 77
INTRODUCTION Many processes in chemical engineering require the separation of one or more of the components of a liquid mixture by treating the mixture with an immiscible solvent in which these components are preferentially soluble. In some cases, purification of a liquid may be the function of the process, in others the extraction of a dissolved component for subsequent processing may be the important aspect. An example of the former is the preparation of pure organic liquids from products of the oil industry. Liquid-Liquid Extractions may also be used as energy-saving processes by, for example, eliminating distillation stages. It is possible, of course that the substance of interest may be heat-sensitive anyway and that distillation is accordingly an unacceptable process. The rate at which a soluble component is transferred from one solvent to another will be dependent, amongst other things on the area of the interface between the two immiscible liquids. Therefore, it is very advantageous for this interface to be formed by droplets and films, the situation being analogous to that existing in packed distillation columns. The Liquid-Liquid Extraction Unit takes the form of a vertically oriented packed column which may be operated either, by filling the column with water and allowing a solvent to flow down the column over the packing, or filling the column with solvent and allowing water to flow up the column over the packing. In either case the process is continuous, both liquids being pumped into the column. Sensing electrodes at the top and bottom of the column determine whether the column is filled with water or with solvent. This is achieved by sensing and maintaining the position of the water level at the appropriate height. A solenoid valve controlling the flow of solvent under gravity from the column is operated by the sensing electrode system. A distillation unit with a fractionating column is included to allow the reclamation of solvent where appropriate.
Page - 78
DIAGRAMS
Page - 79
Page - 80
Page - 81
Page - 82
DESCRIPTION Parts of Equipment 1) Stroke Adjustment Knob 2) Drain Cock 3) Solvent Supply Tank 4) Centrifugal Pump 5) Air Bleed Valve 6) Solenoid Valve 7) (Number Not Exist on Any Diagram) 8) Steel Framework 9) Extra Cross Member 10) (Number Not Exist on Any Diagram) 11) Bottom Plate 12) Adjustable Feet 13) Stainless Steel Plate 14) End Section 15) Flanges 16) Perforated Stainless Steel Plate 17) Flow Control Valve 18) Valve 19) LLE Column (19a and 19b) 20) Distillation Column Boiler 21) (Number Not Exist on Any Diagram) 22) Glass Section 23) Flow Control Valve 24) Flowmeter 25) End Section 26) Stainless Steel Plate 27) Pipeline 28) Injector 29) Condenser 30) Thermometer Page - 83
31) Top Plate 32) Copper Pipes 33) Glass Reflux Divider 34) System Control Panel 35) Distillation Column 36) Receiver Vessel 37) Supply Tank 38) Valve 39) Middle Solvent Tank 40) Polythene Tank 41) Valve 42) Transformer 43) Metering Pump
Brief Description The equipment is mounted in a floor-standing, welded steel framework fitted with adjustable feet. The frame contains an extra cross-member at the front and a similar one at the rear to allow the use of a fork-lift truck. The glass liquid-liquid extraction column is fitted with enlarged end sections which are closed by stainless steel plates, the lower one being bolted to the framework and supporting the column. The four sections of the column proper and the two end plates are all fastened together with flanges, the joints between the sections being sealed with moulded PTFE gaskets. The column is filled with Raschig rings which are supported on a perforated stainless steel plate fitted between the bottom enlarged portion and the lower section of the column. Water for the column is stored in the supply tank (L2) from where it is pumped by the centrifugal pump, through an air bleed valve (V3), a flow control valve (Cl) and a flowmeter (Fl) to an injector mounted in the baseplate and with its exit about 150mm above the plate. Water leaves the top of the column through a pipe, and is collected in a polythene tank (L1). All storage tanks for solvent are constructed in stainless steel. The organic solvent supply tank (L5) provides the feed for the metering pump (F2), the pumping rate of which is varied by a stroke-adjustment knob and indicated by a digital read-out as a percentage of the Page - 84
maximum flow (300 ml/min). Pumped solvent enters the top of the column via an injector similar to that fitted at the base for the water. A sampling and drain cock (V6) is fitted in the solvent feed line. Solvent from the base of the column is returned under gravity to the receiver vessel (L3) via a pipeline which is also fitted with a solenoid valve (C3) and a sampling cock (V9). The Level of the water/solvent interface in the column is determined by. the operation of the solenoid valve (C3) in the solvent outlet pipeline. The operation of this valve is controlled by water-sensing electrodes, one set fitted to the top plate and another set to the bottom plate. A switch (S2) on the system control panel selects the electrodes in use and hence determines whether the interface is at the top or bottom of the column. Each electrode set consists of three stainless steel electrodes, a bare earth electrode to make continuous contact with the water and two others of different lengths insulated to points 5mm from their ends. These insulated electrodes are set to heights differing by 5mm which produces a liquid level differential of 5mm. The purpose of this arrangement is to avoid frequent opening and closing of the solenoid valve which would occur with a simple single-electrode system. The electrical sensing system operates at a low AC voltage and the conduction current through the water is small, the latter being translated into a solenoid-operating voltage by a plug-in module behind the control panel. The receiver vessel (L3) may be connected to the solvent supply vessel via a pipeline and a valve (V4). Thus, liquid which has passed through the column once may be treated again in a batch wise fashion or the valve (V4) may be left open during the extraction to provide a closed circuit, the solvent then being re-circulated continuously. The distillation column boiler (L6), mounted behind the extraction column, is fitted at such a height that liquid may be drained into it from the upper of the three solvent tanks and can be drained from it into the lowest tank. The valve (V7) controls the release of solvent into the boiler. Like pipework, valves and fittings, the boiler is constructed in stainless steel. Heating is by means of two 500W cartridge elements inserted at the base of the boiler and boiler temperature is indicated on a thermometer in the side. The boiler lid is perforated where the distillation column is fitted and three blind tapped holes around this area accept bolts fixing the column flange to the boiler.
Page - 85
The column proper is made up of a glass section containing four sieve plates. The glass reflux divider bolts to the column top and to the stainless-steel condenser above it with bolts and flanges and all the sections are sealed together with moulded PTFE gaskets. The reflux divider is fitted with a thermometer (T2) to indicate the vapor temperature beneath the divider. The condensate outlet tube and the thermometer tube on the divider are terminated with glass screw - thread connectors and screw caps to form secure but demountable connections. The condenser is vented to atmosphere at the top, and its jacket is water-cooled by a supply via the copper pipes at the rear. The boiler, distillation column and condenser are all lagged to minimize heat losses. Condensate from the reflux divider flows under gravity into the middle solvent tank (L4) via the flow control valve (C2) which thus determines the reflux ratio. The contents of the middle tank (L4) can be drained into the solvent supply tank by opening the valve (V5) between the two. The three solvent tanks (L3), (L4), (L5) are vented to atmosphere through a vent pipe which is inserted into the top of the condenser. Solvent levels in the tanks and boiler are indicated with glass sight tubes protected by clear polyethylene sleeves. Control of the equipment is simplified with a system diagram panel. The complete solvent/water flow system is shown with electrical controls at the appropriate points on the diagram. These are mains on/off switch (S1), water pump on/off switch (S3), solvent pump on/off switch (S4), boiler heater switch (S5) and power regulator (R1), electrode changeover switch (S2), and solenoid valve “open” indicator light. The four mains supply switches are selfilluminating in the “on” position. A mains transformer is fitted when the electrical supply is 120V, 60Hz A.C.
CONNECTION TO SERVICES ELECTRICAL SUPPLY FOR VERSION UOP5-A: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply, for this equipment is 220-240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: Page - 86
GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 10 amp
ELECTRICAL SUPPLY FOR VERSION UOP5-B: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 120V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 15 amp
Note: A transformer is fitted to this version to step up the supply voltage from 120V AC to 240V AC. The transformer is mounted on the equipment frame behind the solvent pump.
ELECTRICAL SUPPLY FOR VERSION UOP5-G: The equipment requires connection to a single phase, fused electrical supply. The standard electrical supply for this equipment is 220-240V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows:
GREEN/YELLOW - EARTH BROWN
- LIVE (HOT)
BLUE
- NEUTRAL
FUSE RATING
- 10 amp
Page - 87
COMMISSIONING The following procedure is intended for initially checking that the equipment is operating correctly after assembly. Water is used in place of organic solvents on the grounds of safety. Before proceeding with the commissioning ensure that the gearbox on the solvent pump has been filled with oil (indicated by the presence of oil half way up the sight gauge on the side of the gearbox). 1. Close all valves on the equipment - including drain valves. Check longest and middle electrodes at top of extraction column, and shortest and middle electrodes at bottom of column are approximately 5mm apart. Adjust if necessary. 2. Fill tank L2 with tap water. 3. Connect the equipment to the electrical supply. 4. Set electrode switch to top position (switch S2). Operate mains switch S1 - check S3, S4 and S5 are 'OFF' and S1 is illuminated. Check solenoid valve C3 is open (light on). Set the electrode switch to bottom position then check that solenoid valve C3 is still open (light on). 5. Open vent valve V3 then switch on water pump (switch S3). Allow water pump to prime (water discharges at V3), then close vent valve V3. 6. Open control valve C1. Check flow of water on flowmeter FI. Check water is delivered to injector at base of extraction column. 7. Allow column to start filling with water at a slow rate. The solenoid valve C3 will be open (light on) until water covers the short electrode when C3 will close (light off). Open the drain valve (V11) at the base of the extraction column and drain water until the tip of the short electrode is exposed and the valve will again open. 8. Close drain valve (V11) in base of column. Open control valve Cl and adjust to give full scale reading on flowmeter F1. C3 will close again when the water level reaches the short electrode then the column will gradually fill. Leave the electrode switch in the down position. Check C3 is still closed (light off). Wait for water level to reach the top plate i.e. column completely full. Make sure water flows from the top of the column to the polythene storage tank (L1). 9. Switch S2 to top electrodes position. Check C3 remains closed. Close the flowmeter control valve Cl. Open the drain valve V11 at the base of the column and allow water Page - 88
to drain until the water level falls below the long electrode. Check valve C3 opens (light on). Water will drain into tank L3 until level in column equals level in tank L3. 10. Check pipework and column for leaks. 11. Switch off water pump (switch S3). Drain all remaining water from column through drain valve V11 in base of column. 12. Fill vessel L3 with tap water through top filler. Check sight gauge on L3 operates. 13. Half fill vessel L4 with tap water through top filler. Check sight gauge on L4 operates. 14. Open valve V7. Allow boiler L6 to l /3rd fill with water. Close valve V7. Check sight gauge on L6 operates. 15. Open valve V4. Allow vessel L5 to fill with water - allow L3 to drain. Close valve V4. Check, sight gauge on L5 operates. 16. Set calibration valve V8 to the column position, open bleed valve V13 at the solvent pump discharge and place a suitable container beneath the valve to allow the water which will discharge to be collected. Set pump delivery to 100% (F2) then switch on solvent pump (switch S4). When water flows from bleed valve V13 close valve V13 and check that water is delivered to injector at top of extraction column. Set calibration valve V8 to the calibrate position and check that water is delivered to the bypass. Close calibration valve V8. Check F2 regulates delivery to extraction column. Switch off solvent pump (switch S4). Check system for leaks. DRAIN WATER.
NOTE: Solvent pump needs to be calibrated before experiments can take place. 17. Connect cooling water to lower connection on condenser. Connect top connection on condenser to drain. 18. Turn on cooling water supply. Check flow of water to drain. Check for leaks. 19. Set power control R1 to minimum (fully anti-clockwise). Switch on heating elements (switch S5). Rotate power control R1 to maximum (fully clockwise). Check temperature of water increases (Thermometer Tl). Check boiler for leaks. Allow water to boil. When condensate collects in reflux divide open control valve C2. Check water flows from reflux divider to vessel L4. 20. Set power control R1 to minimum (fully anti-clockwise) then drain the boiler by opening valve V10. When the level falls below the level switch power should be disconnected (S5 not illuminated). Switch off the boiler (S5). 21. Disconnect the electrical supply, turn off cooling water and drain all water from the equipment. Page - 89
Instruction Manual
TRAY DRIER APPARATUS
Page - 90
INTRODUCTION A large number of manufacturing processes necessitate the drying of a product or material and the equipment used in these industrial operations depends on the particular process and type of material being dried. For example, the requirements for food processing are more stringent than for agricultural fertilizer materials, and the design of driers for these purposes will be dictated by the relative importance of such factors as heat sensitivity, porosity, bulk density and particle size of the dried material. In fact, since the dried solid is generally a valuable product, its shape, color, stability, stickiness and hence its overall sale ability, all depend upon the drying processes to which it has been subjected. Although there are many different types and operating characteristics of industrial driers, the Tray Drier has been designed to provide an experimental facility based on one of the most fundamental designs. Drying involves the transfer of liquid from a wet solid to an unsaturated gas phase such as air, and the solid itself can exert a considerable influence on the drying process. The Tray Drier enables the basic principles of drying to be investigated and students of process engineering may examine the problems of fluid mechanics, surface chemistry, solid structure and mass and heat transfer associated with general drying behavior.
Page - 91
DIAGRAMS
FIGURE-A Page - 92
FIGURE-B Page - 93
DESCRIPTION Parts of Equipment For Figure-A 1) Heating Section of the Tunnel 2) Drying Section of the Tunnel 3) Weight Balance 4) Four Sample Trays 5) Tray Support 6) Support Legs 7) Aspirated Psychrometer 8) (Unknown on Figure) 9) (Number Not Present on Figure) 10) Balance Clamp
For Figure-B 1) Aspirated Psychrometer 2) Psychrometer Bracket 3) Plug 4) Switch 5) Speed Control Knob 6) Switch 7) Power Control Knob 8) Fan 9) Aperture Upstream 10) (Unknown on Figure) 11) Digital Balance 12) (Unknown on Figure) 13) Tunnel Access Door 14) Sample Trays 15) Aperture Downstream
Page - 94
Brief Description The apparatus comprises of an air duct mounted on a floor standing frame to give a comfortable working height for the operator. Air is drawn into the duct through a mesh guard by a motor driven axial flow fan impeller whose speed can be controlled to produce a range of air velocities up to 1.5 m/s in the duct. The air passes over an electrically heated element controlled by a power regulator to provide a variation in air temperature up to a maximum of 80°C at low air velocities. The air passes into the central section of the duct where four trays of material to be dried are suspended in the air stream. The trays are carried on a support frame which is attached to a digital balance mounted above the duct and on which the total weight is continuously indicated. The trays are inserted or removed from the duct, through a latched side door with a glass panel for viewing purposes. After passing over the drying trays, the air is discharged at atmosphere through an outlet duct section where a vane anemometer, with resolution counter for measurement of air velocity, can be positioned. Wet and dry bulb temperatures of the air are measured using an aspirated psychrometer which is powered from a socket outlet on the control panel mounted on the duct. Access points for the psychrometer are provided both upstream and downstream of the drying trays and are covered by flaps when not in use.
Page - 95
CONNECTION TO SERVICES ELECTRICAL SUPPLY FOR VERSION UOP8-A: The equipment requires connection to a single phase fused electrical supply. The standard electrical supply for this equipment is 220/240V, 50Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW BROWN BLUE FUSE RATING
-
EARTH LIVE (HOT) NEUTRAL 13 amp
ELECTRICAL SUPPLY FOR VERSION UOP8-B: When supplied for operation from a non-standard electrical supply (120V, 60Hz), the equipment incorporates a transformer of appropriate current rating. In this case the transformer is attached to the left-hand leg of the drier. An in-line connector is provided to connect the drier to the transformer. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made as follows: GREEN/YELLOW BROWN BLUE FUSE RATING
-
EARTH LIVE (HOT) NEUTRAL 30 amp
ELECTRICAL SUPPLY FOR VERSION UOP8-G: The equipment requires connection to a single phase fused electrical supply. The standard electrical supply for this equipment is 220/240V, 60Hz. Check that the voltage and frequency of the electrical supply agree with the label attached to the supply cable on the equipment. Connection should be made to the supply cable as follows: GREEN/YELLOW BROWN BLUE FUSE RATING
-
EARTH LIVE (HOT) NEUTRAL 13 amp
Page - 96
COMMISSIONING 1. Connect the equipment to the electrical supply. Check switches are in the OFF position. Check that the power supply, for the digital balance is connected and plugged into the mains outlet socket at the rear of the heating section. 2. Disconnect the aspirated psychrometer from the electrical console by removing the plug. 3. Remove the water chamber from the handle of the aspirated psychrometer. Fill the chamber with distilled water and replace the chamber, ensuring that the wick is immersed. 4. Replace the psychrometer into its bracket and reconnect the plug at the electrical console. Raise the psychrometer until the inlet duct is horizontal. Check that the electrical fan, within the psychrometer, operates and observe that the dry and wet bulb temperatures are indicated satisfactorily on the thermometers. Replace the psychrometer into its bracket and check that the electrical fan switches off. NOTE: In normal operation, the inlet duct of the psychrometer is inserted into the tunnel through the aperture upstream or downstream of the working section. These apertures are shielded to prevent loss of air when the psychrometer is not in use. 5. Close the tunnel access door. Operate the fan on/off switch, rotate the fan speed control knob clockwise and check that the fan operates. 6. With the fan operating, operate the heater on/off switch, rotate the power control knob clockwise and check that the air is heated by the electrical elements downstream of the fan. NOTE: The heating elements are thermostatically protected. In the event of overheating, power will be cut to the elements until a normal operating temperature is attained. This process may be speeded up by operating the fan at full speed. 7. Set the fan and heater switches to the OFF position. Depress the ON button on the digital balance and observe the digital reading. Check operation of the tare by depressing the tare button, the display should zero. Open the access door in the wall of the tunnel and place a suitable weight on the sample trays. Check correct operation of the balance. Remove the weight from the sample tray and check balance returns to original reading. Page - 97
NOTE: The two hooks on the tray support are adjustable in position to allow the trays to remain horizontal when suspended from the balance. If adjustment is necessary, it should be carried out with the trays in position but empty. When filling the trays with samples for drying, ensure that the filling is evenly distributed to maintain the trays in a horizontal position. To perform the experiments outlined in the laboratory sheets, the following will be required: a. A supply of sand or alternative medium for drying will be required, together with sieves for grading purposes. b. A supply of water will be required for wetting the samples. c. A stop watch will be required.
Page - 98
Instruction Manual
FLUIDIZED BED DRIER APPARATUS
Page - 99
INTRODUCTION When a stream of gas is passed upwards through a bed of material at a certain velocity the bed will first expand, then become suspended and agitated by the gas stream to form a fluidized bed. This has the appearance of boiling liquid due to the formation of many small bubbles-the so-called ‘bubbling fluidization’. At higher gas velocity, larger bubbles and plugs of material are formed resulting in a more violent type of fluidization called slugging or spouting. The optimum operating gas velocity for bubbling fluidization lies above the minimum fluidizing velocity but below the velocity of entrainment of the material. If a bed of wet material is fluidized by a heated air stream, as in the laboratory batch dryer, the conditions are ideal for drying. The very efficient contact between gas and solid particles results in heat transfer rate causing evaporation (mass transfer) of moisture which is carried away with the exit air. The same principles apply for industrial fluid bed dryers-both batch and continuous types; therefore, the laboratory fluid bed dryer can be used to assess the feasibility of different materials for large scale fluidized drying.
Page - 100
DIAGRAM
Page - 101
DESCRIPTION Parts of Equipment 1) Jar Containing Sold Particles Need to be Dried 2) Control Unit (Having On/Off Control and Air Pump Control and Heating Element)
Brief Description The drier can be used with a wide range of materials including fine powders, coarse particles, crystals, granules, even slurries or pastes (after decanting or pre-drying or by spraying onto an initial bed of the dried material). Heat sensitive materials including foodstuffs like peas, wheat or lentils may be dried at relatively low temperatures. The drier is of simple, compact design, conveniently portable and easy to operate, the only requirement being a mains power supply. Air is drawn through a mesh filter in the base of the cabinet and blown by a centrifugal fan over a 2kW finned electrical heater and through a stainless-steel filter gauze before being delivered to the distributor gauze at the base of the drier body which supports the bed and distributes the air uniformly. The air blower is controlled by a thyristor circuit to give a smooth vibration over a wide range of motor speeds, enabling efficient fluidization to be achieved for a variety of materials and giving fine control of the drying temperature. Readings are selected and displayed using a digital meter. The unit can be manually operated or interval timing can be carried out with the timer unit, which gives a 0-10-minute timing range and an alarm facility to notify completion of the operation. The tube unit locks into position on the cabinet top by a simple bayonet fitting and the base of the tube is removeable to allow replacement of the distributor gauze. A filter bag is employed to retain any stray particles of the sample being fluidized, allowing the passage of the exit gasses.
Page - 102
CONNECTION TO SERVICES ELECTRICAL SUPPLY FT31-A:
220-240V / Single Phase / 50Hz
FT31-B:
120V / Single Phase / 60Hz
Power Consumption:
3kW
TECHNICAL SPECIFICATIONS Temperature Range:
20 to 100oC (±1oC)
Timer Range:
0 to 10 minutes
Max. Sample Weight
5kg
COMMISSIONING 1. Connect power plug to power source. 2. Turn on air pump to check that it is working correctly. 3. Turn on heating element to check that it is heating the air or not. 4. Apparatus is ready for experiment.
Page - 103
Lab Manuals (Experiments)
1. General Safety Precautions 2. Experiment 1 (Gas Diffusion Coefficients Apparatus)
3. Experiment 2 (Ion Exchange Apparatus)
4. Experiment 3 (Ion Exchange Apparatus)
5. Experiment 4 (Batch Distillation Apparatus)
6. Experiment 5 (Batch Distillation Apparatus)
7. Experiment 6 (Batch Distillation Apparatus)
8. Experiment 7 (Continuous Distillation Apparatus)
9. Experiment 8 (Continuous Distillation Apparatus)
10.Experiment 9 (Gas Absorption Apparatus)
11.Experiment 10 (Gas Absorption Apparatus)
12.Experiment 11 (Liquid-Liquid Extraction Apparatus)
13.Experiment 12 (Liquid-Liquid Extraction Apparatus)
14.Experiment 13 (Tray Drier Apparatus)
15.Experiment 14 (Tray Drier Apparatus)
16. Experiment 15 (Fluidized Bed Drier Apparatus)
Page - 104
General Safety Precautions
Precautions: (Common for all experiments) 1. Personal Safety:
Check the proper working of residual current circuit breaker (RCCB).
Ensure that there is no leakage of any fluid especially water to contact with electrical supply.
Always disconnect equipment from the electrical supply when not in use.
Use fire extinguishers in case of fire or explosion.
Do not smoke because flammable liquids, gases, and vapors can cause fire.
2. Equipment Safety:
Do not exceed upper limits of operating conditions (T = Temp., P = Pressure, F = Flowrate, S = Speed).
Check proper working of equipment ON/OFF Circuit Breaker or Switch.
Do not use equipment without lab attendant.
Do not try to become a juggler with equipment but if you don’t know anything then report and ask for it.
3. Chemical Safety:
Drain any residual water present in the apparatus
Do not expose flammable organic fluids with flame or spark.
Do not eat any food in chemical laboratory because its contamination with any dangerous chemical can cause death.
Do not taste any chemical it can cause death.
For dilution purposes of acids and alkalis, the acid or alkali should be added slowly drop by drop into water while stirring. The reverse process surely causes explosive phase change of water. (e.g. H2SO4 dilution).
Gloves and Googles must be worn whenever there is a risk to the eyes.
Wear lab coat.
Page - 105
Experiment 1 (GAS DIFFUSION COEFFICIENTS APPARATUS) Objective: To determine the diffusion coefficient of a gas by evaporation from a liquid surface.
Equipment Setup / Apparatus: Gaseous Diffusion Coefficient Unit
Reagents: Water, Acetone, Detergent.
Theory: The diffusivity of the vapor of a volatile liquid in air can be conveniently determined by WINKLEMANN’S method in which liquid is contained in a narrow diameter vertical tube, maintained at a constant temperature, and an air stream is passed over the top of the tube to ensure that mass transfer of the acetone will take place from the surface of the liquid to the air stream by molecular diffusion.
Page - 106
Consult the book “TRANSPORT PHENOMENA” 2nd Ed., Section “MASS TRANSPORT” by “R. Byron Bird” for further elaboration and derivation of relationships used in calculations.
Procedure: 1) Use detergent solution to clean the capillary tube. A weak solution of the detergent should be injected into the tube slowly as shown below:
2) To empty the tube simply shake the tube whilst it is upside down until all detergent solution has gone. Repeat these two steps for water as a fluid in order to remove any detergent solution left. 3) The capillary tube can now be primed (filled) with acetone using the same procedure. The depth of Acetone should be approximately 35mm when filled. 4) Insert the capillary tube into apparatus. 5) Connect AIR TUBE to one end of the “T” piece. 6) Adjust the object lens in such a way as to see the capillary tube meniscus. 7) Adjust the position of the viewing lens in or out of the microscope body as necessary for clearer vision of meniscus level. (Note that when viewing the capillary tube the image will be upside down, so that the bottom of the tube is at the top of the image.) 8) Record the level inside the capillary tube. 9) Switch on the air pump. Switch on temperature controlled water bath, adjust set point on controller to 40oC and obtain a steady temperature. 10) After some suitable time period, approximately 45 mints record the change in level inside the capillary tube. 11) Repeat the procedure to take at least three to four readings. At the end switch off the apparatus. Page - 107
Data Analysis: (L-Lo) at time t = Reading on Vernier at time (t) - Initial reading on Vernier at (t = 0sec)
Results: Time from commencement
Change in Liquid Level
of Experiment.
(L-Lo)
𝑡 (𝐿 − 𝐿𝑜 )
ks (killo seconds)
mm
ks/mm
1) Plot 𝑡 𝑜𝑛 𝑦 𝑎𝑥𝑖𝑠 (𝐿 − 𝐿𝑜 ) (𝐿 − 𝐿𝑜 ) 𝑜𝑛 𝑥 𝑎𝑥𝑖𝑠 And determine the slope of the plot and name it “s”. 𝑦2 − 𝑦1 𝑆= =? 𝑥2 − 𝑥1 2) Use the following formulas to determine the mass diffusivity:
𝔇𝐴𝐵 = 𝔇𝐴𝐵
𝜌𝐿 𝐶𝐵𝑚 𝑠(2𝑀𝐶𝐴 𝐶𝑇 )
𝑚2 = 𝑀𝑎𝑠𝑠 𝐷𝑖𝑓𝑓𝑢𝑠𝑖𝑣𝑖𝑡𝑦 𝑜𝑓 𝐴𝑐𝑒𝑡𝑜𝑛𝑒 𝑖𝑛 𝐴𝑖𝑟 ( ) 𝑠
𝐶𝐴 = 𝑆𝑎𝑡𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑎𝑡 𝑖𝑛𝑡𝑒𝑟𝑓𝑎𝑐𝑒 (
𝑘𝑚𝑜𝑙 ) 𝑚3
Page - 108
𝜌𝐿 = 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑡ℎ𝑒 𝐿𝑖𝑞𝑢𝑖𝑑 (𝐴𝑐𝑒𝑡𝑜𝑛𝑒) = 790 𝐶𝐵𝑚 =
𝑘𝑔 𝑚3
(𝐶𝐵1 − 𝐶𝐵2 ) 𝑘𝑚𝑜𝑙 = 𝐿𝑜𝑔𝑎𝑟𝑖𝑡ℎ𝑚𝑖𝑐 𝑚𝑒𝑎𝑛 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑣𝑎𝑝𝑜𝑢𝑟 ( 3 ) 𝐶 𝑚 ln(𝐶𝐵1 ) 𝐵2
𝐶𝐵1 = 𝐶𝑇 𝐶𝑇 =
1 𝑇𝑎𝑏𝑠 𝑘𝑚𝑜𝑙 ( ) = 𝑇𝑜𝑡𝑎𝑙 𝑀𝑜𝑙𝑎𝑟 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 ( 3 ) 𝑉𝑚 𝑇𝑎 𝑚
𝑚3 𝑉𝑚 = 22.414 𝑘𝑚𝑜𝑙 𝑇𝑎𝑏𝑠 = 273 𝐾 𝑇𝑎 = 313𝐾 = 40𝑜 𝐶 (𝑆𝑒𝑡 𝑃𝑜𝑖𝑛𝑡 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒) 𝐶𝐵2 = (
𝑃𝑎 − 𝑃𝑣 )𝐶𝑇 𝑃𝑎
𝑃𝑎 = 101.3
𝑘𝑁 𝑚2
𝑃𝑣 = 𝑉𝑎𝑝𝑜𝑟 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑜𝑓 𝐴𝑐𝑒𝑡𝑜𝑛𝑒 = 𝑓(𝑇) 𝐴𝑡 40𝑜 𝐶 (313𝐾) 𝑡ℎ𝑒 𝑃𝑣 = 56
𝑘𝑁 𝑚2
𝑀 = 𝑀𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐴𝑐𝑒𝑡𝑜𝑛𝑒 = 58.08
𝑘𝑔 𝑘𝑚𝑜𝑙
𝑃𝑣 𝐶𝐴 = ( )𝐶𝑇 𝑃𝑎 Note: 1) To prevent the acetone from boiling do not set the temperature controller above 50oC. 2) If the experiment is performed with the water bath set to different temperatures than 40oC it will be necessary to obtain suitable values for Pv. 3) The experiment can be repeated at different temperatures and the effect of temperature on the mass diffusivity can be study if necessary.
𝔇𝐴𝐵 = 𝑓(𝑇, 𝑃)
Page - 109
Sample Results: A set of typical results are presented overleaf for information. Diffusivity of Acetone in air at 40oC (313K) and atmospheric pressure (Pa = 101.3kPa) from the following experimental data. Time from commencement of Experiment
Liquid Level (L-Lo)
𝑡 (𝐿 − 𝐿𝑜 )
mm 0.00 2.20 4.20 6.30 8.80 10.80 12.40 34.50 36.10 37.30 38.90 40.80 42.00
ks/mm Undetermined Form 1.636 1.714 1.771 1.807 1.850 1.887 2.283 2.314 2.339 2.360 2.385 2.407
ks 0.000 3.600 7.200 11.160 15.900 19.980 23.400 78.780 83.520 87.240 91.800 97.320 101.100 𝑡
Plot of (𝐿−𝐿 ) vs (𝐿 − 𝐿𝑜 ). 𝑜
t/(L-Lo) vs (L-Lo) Line 3.000 2.500 2.000 1.500 1.000 0.500 0.000 0
5
10
15
20
25
30
35
40
45
Page - 110
Sample Calculations: Point-1: (x1, y1) = (2.200, 1.636) Point-2: (x2, y2) = (42.000, 2.407) 𝑆=
𝑦2 − 𝑦1 2.407 − 1.636 𝑘𝑠 𝑠 𝑠 9 7 = = 0.0194 = 0.0194×10 = 1.94×10 𝑥2 − 𝑥1 42.000 − 2.200 (𝑚𝑚)2 𝑚2 𝑚2
𝐶𝑇 =
1 𝑇𝑎𝑏𝑠 ( )= 𝑉𝑚 𝑇𝑎
1 22.414
𝐶𝐵1 = 𝐶𝑇 = 0.0389
𝐶𝐵2
𝑚3
×
273𝐾 𝑘𝑚𝑜𝑙 = 0.0389 313𝐾 𝑚3
𝑘𝑚𝑜𝑙
𝑘𝑚𝑜𝑙 𝑚3
𝑘𝑁 𝑘𝑁 101.3 2 − 56 2 𝑃𝑎 − 𝑃𝑣 𝑚 𝑚 ×0.0389 𝑘𝑚𝑜𝑙 = 0.0174 𝑘𝑚𝑜𝑙 =( ) 𝐶𝑇 = 𝑘𝑁 𝑃𝑎 𝑚3 𝑚3 101.3 2 𝑚
𝐶𝐵𝑚
𝑘𝑚𝑜𝑙 𝑘𝑚𝑜𝑙 (𝐶𝐵1 − 𝐶𝐵2 ) 0.0389 𝑚3 − 0.0174 𝑚3 𝑘𝑚𝑜𝑙 = = = 0.0267 𝐶 𝑘𝑚𝑜𝑙 𝑚3 ln(𝐶𝐵1 ) 0.0389 3 𝑚 𝐵2 ln( 𝑘𝑚𝑜𝑙 ) 0.0174 𝑚3
𝑘𝑁 56 2 𝑃𝑣 𝑚 ×0.0389 𝑘𝑚𝑜𝑙 = 0.0215 𝑘𝑚𝑜𝑙 𝐶𝐴 = ( ) 𝐶𝑇 = 𝑘𝑁 𝑃𝑎 𝑚3 𝑚3 101.3 2 𝑚 𝑘𝑔
𝔇𝐴𝐵
𝑘𝑚𝑜𝑙
790 3 ×0.0267 𝜌𝐿 𝐶𝐵𝑚 𝑚 𝑚3 = = 𝑠(2𝑀𝐶𝐴 𝐶𝑇 ) 1.94×107 𝑠 ×2×58.08 𝑘𝑔 ×0.0215 𝑘𝑚𝑜𝑙 ×0.0389 𝑘𝑚𝑜𝑙 2 3 3 𝑚
−5
𝔇𝐴𝐵 = 1.12×10
𝑘𝑚𝑜𝑙
𝑚
𝑚
𝑚2 𝑠
Page - 111
Experiment 2 (ION EXCHANGE APPARATUS) Objective: To study the demineralization of water and to determine the exchange capacities of a hydrogen ion cation exchanger and an anion exchanger.
Equipment Setup / Apparatus: Ion Exchange Unit, Beaker 500 ml, Glass Stirrer.
Reagents: Cation Exchange Resin, Anion Exchange Resin, HCl, NaOH, Test Water containing dissolved solids, Distilled or Demineralized Water. Page - 112
Theory: (DEMINERALIZATION) The removal of all dissolved salts from water can be achieved by using a two-stage ion exchange process. The water is first passed through a strong cation exchanger working on the hydrogen ion cycle, when cations in the water are replaced by H+ ions, giving a solution of acids. This is then passed through an anion exchanger in the hydroxyl ion form, when the acid ions are replaced by OH- ions, which with the H+ ions, produce water. It is often sufficient to use a weakly basic anion exchanger, which will remove all anions except HC03- (due to dissolved carbon dioxide) and H3Si04- (due to dissolved silica). For a higher quality product water, a strongly basic anion exchanger must be used as the final stage, but it is generally more economical to precede this with a weakly basic anion exchanger of high exchange capacity to remove the bulk of the anions, and a degassing tower to release CO2 from solution. The strongly basic resin is then required only to remove silica and any residuals of other anions which may still be present. This process can reduce total dissolved solids to below 1mg/liter. Demineralization can also be performed in a single stage by using a mixed bed of strong cation and anion exchangers. The water repeatedly comes in contact with the two resins alternately, and is ultimately of very high purity. To enable the two resins to be regenerated with sulphuric acid and sodium hydroxide respectively, they are first stratified with an upward flow of water, the anion resin being of lower density and therefore carried to the top. After regeneration, the two resins are re-mixed by compressed air.
Procedure: A. Preliminary Requirements 1) Fill cation column to a depth of 300mm with a cation exchanger resin in the hydrogen ion form. 2) Fill anion column to a depth of 300mm with an anion exchange resin in the hydroxyl form. 3) Fill tank A with 100ml of a 10% HCl solution. 4) Fill tank B with 100ml of a 5% NaOH solution. 5) Fill tank C with test water containing 800 to 1000 mg/liter of dissolved solids. 6) Fill tank D with distilled or demineralized water.
Page - 113
7) If tap water is used, the concentrations of the principal cations and anions, as well as the total dissolved solids, must be determined if not already known. 8) From a knowledge of the concentrations of the main cations and anions in the water to be used, calculate the total strength in meq/liter. 9) This will be used in calculating the exchange capacities of the two resins. The electrical conductivity should also be measured.
B. Demineralization: 1) Select tank C, open valves 2, 13 and 15. Set flow rate to between 50 and 70 ml/min. 2) Note time at which flow is started and take conductivity readings at 5 minute intervals. 3) At 20 minute intervals draw off samples from valve 10 and measure pH value. 4) Note the time when the conductivity of the demineralized water begins to rise, i.e. the breakthrough point at which one of the resins has become exhausted. 5) As soon as possible after this point, take another small sample from valve no. 16 and measure its pH. 6) If this pH is higher than the values previously recorded, it indicates that the cation exchanger has become exhausted. 7) It is advisable to confirm this by drawing one or two further samples for pH determination. 8) The experiment should be stopped at this point, and the exchange capacity of the cation exchanger calculated. 9) It is then possible to determine the exchange capacity of the anion exchanger in this experiment. 10) If, on the other hand, the pH of the cation exchanger effluent continues at a low value, the rising conductivity of the final effluent indicates that the anion exchanger is exhausted, and its capacity can be calculated. 11) In the latter event, the exchange capacity of the cation exchanger can be determined by continuing the flow of water through the first column only, collecting the water which passes through it and measuring pH values until the breakthrough point, when the pH begins to rise.
Page - 114
In all of the figures:
C. Backwashing: 1) Each column should be separately backwashed. 2) In each case, the rate of backwashing should be controlled to give not more than 50% expansion of the bed. 3) Measure the final depths of the two beds.
Page - 115
D. Cation Regeneration: 1) Regenerate the cation exchanger. 2) Select tank A, open valves 2 and 12. Follow the acid with distilled or demineralized water from tank D, to flush out any surplus acid. 3) Check pH of effluent and continue flushing until pH has returned to above 5.0.
E. Anion Regeneration: 1) Regenerate the anion exchanger. 2) Select tank B, open valves 1 and 15, followed by distilled or demineralized water from tank D until pH of the effluent has returned to below 9.0.
Page - 116
Data Analysis: In the demineralization experiment, the breakthrough point is detected by readings of pH (for the cation exchanger) or conductivity (for the anion exchanger) instead of by direct measurement of concentrations. Time (min)
0
5
10
15
20
25
30
35
40
45
50
55
60
Conductivity PH Values
In order to calculate the exchange capacities in terms of milli-equivalents (meq), it is necessary to convert pH or conductivity readings to meq/liter.
(a) To convert pH values to meq/liter. If pH reading is “x” Hydrogen ion concentration = 10-x moles/liter = 103-x meq/liter
(b) To convert conductivity values to meq/liter. For a water with a given content of salts, the electrical conductivity is closely proportional to the concentration of total dissolved solids. Although these solids consist of several salts of varying electrolytic properties, it is sufficiently accurate to assume that electrical conductivity is also proportional to the the total concentration in terms of meq/liter. The constant of proportionality was established by determination of the electrical conductivity and the strength of meq/liter of the raw water. Hence the electrical conductivity of the demineralized water can be converted to meq/liter. In any event these figures should be very low.
(c) Other Calculations Final Depths: CATION = _______________ ANION = _______________
Page - 117
(π×15×10−3 )2 Wet Volume = ×Final Depth 4 Exchange capacities can now be calculated. 𝐸𝑥𝑐ℎ𝑎𝑛𝑔𝑒 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 =
𝑆𝑜𝑑𝑖𝑢𝑚 𝐼𝑜𝑛 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑊𝑒𝑡 𝐵𝑒𝑑
Page - 118
Experiment 3 (ION EXCHANGE APPARATUS) Objective: To determine the regeneration efficiency of cation resin and an anion resin.
Equipment Setup / Apparatus: Ion Exchange Unit, Beaker 500 ml, Glass Stirrer.
Reagents: Cation Exchange Resin, Anion Exchange Resin, HCl, NaOH, Test Water containing dissolved solids, Distilled or Demineralized Water. Page - 119
Theory: (REGENERATION) Theoretically, for every milli-equivalent of hardness as CaCO3 removed from the water under treatment, one milli-equivalent of NaCl is required for regeneration, i.e. l g of hardness as CaCO3 removed requires 1.17 g NaCl for regeneration (Molecular weights: CaCO3 50.0, NaCl 58.5). In practice, it is not possible to achieve complete regeneration with this quantity of NaCl, since this would require an unacceptable long contact period. Larger quantities of NaCl are therefore used, generally twice or more the theoretical amount. Tire regeneration efficiency is thus around 50%. A high level of regeneration gives a resin with a high exchange capacity approaching its theoretical, but it is uneconomic to operate at such a rate that this capacity is fully used in softening. In other words, a high regeneration efficiency is associated with a low degree of column utilization, and vice versa. The practical operation of an ion-exchange bed is therefore a compromise in which the regeneration efficiency and the column utilization are both in the region of 50% (Optimization is requires). After regeneration, distilled or demineralized water is passed through the bed to wash out any remaining regenerator. Water to be treated by ion exchange must be free of suspended solids which would block the passage-ways, reduce flow rates and interfere with the exchange process. To remove fine solids which may get into the bed, and to release any air pockets, the column is backwashed periodically by an upward flow of water which fluidizes the bed and agitates the resin beads. The rate of flow of water through the bed in softening is usually not more than 40 ml/(min.cm2) of surface area of bed. Regeneration rates are about one tenth of this.
Page - 120
Procedure: A. For Cation Resin Regeneration Efficiency 1) Fill cation column to a depth of 300mm with a cation exchanger resin in the hydrogen ion form. 2) Fill anion column to a depth of 300mm with an anion exchange resin in the hydroxyl form. 3) Fill tank A with 100ml of a 10% HCl solution. 4) Fill tank B with 100ml of a 5% NaOH solution. 5) Fill tank C with test water containing 800 to 1000 mg/liter of dissolved solids. 6) Fill tank D with distilled or demineralized water. 7) If tap water is used, the concentrations of the principal cations and anions, as well as the total dissolved solids, must be determined if not already known. 8) From a knowledge of the concentrations of the main cations and anions in the water to be used, calculate the total strength in meq/liter. 9) This will be used in calculating the regeneration efficiency of the two resins. The electrical conductivity should also be measured. 10) Backwash: Select tank D, open valves 3 and 6. 11) Regenerate: Select tank A, open valves 2 and 10. Collect whole of the solution.
B. For Anion Resin Regeneration Efficiency 1) To determine the regeneration efficiency of the anion resin it will be necessary to carry out the full demineralization experiment. 2) Since the exchange capacities of cation resins are generally greater than those of anion resins, it is expected that the anion resin will be first to be exhausted.
Page - 121
Data Analysis: Final Depths: CATION = _______________ ANION = _______________
Sodium ion concentration (meq/ml) = (π×15×10−3 )2 Volume of solution used (ml) = ×Final Depth 4 Exchange capacities can now be calculated. Theoretical Exchange Capacity =
Sodium Ion Concentration Volume of NaOH used
Original quantity of NaOH used = Amount of NaOH collected = Actual Exchange Capacity = Original Quantity – Amount Used Regeneration Efficiency =
Actual Exchange Capacity Theoretical Exchange Capacity
Page - 122
Experiment 4 (BATCH DISTILLATION APPARATUS) Objective: To determine the pressure, drop over the distillation column for various boil-up rates.
Equipment Setup / Apparatus: Batch Distillation Apparatus, Measuring Cylinder 250ml, Stop Watch
Reagents: Ethanol, Water
Page - 123
Theory: The total pressure drop across each tray is the sum of that caused by the restriction of the holes in the sieve tray, and that caused by passing through the liquid (foam) on top of the tray. As the velocity of the vapors passing up the column increases then so does the overall pressure drop. The velocity is controlled by varying the boil-up rate which is done by varying the power input to the reboiler. Under conditions with no liquid present, the sieve trays will behave like an orifice in that the pressure drop will be proportional to the square of the velocity. Due to the fact that there is a liquid head however, this square relationship does not become apparent until the head of liquid has been overcome and foaming is taking place. In a graph of pressure drop vs. boil up rate (log/log), at low boil-up rates the pressure drop will remain fairly constant until foaming occurs when the pressure drop would be expected to rise sharply for unit increases in boil-up rate.
Procedure: 1) Make 10 Liters of mixture of 50 mole percent ethanol and 50mol percent water. Species
Formula
Molar Mass Density Mole Fraction (kg/kmole) (kg/m³)
Mixture Data
Ethanol (Component A) C2H5OH
46
789
0.5
H2O
18
1000
0.5
Water (Component B)
Required Volume of Mixture = V = 10 Liters nA nB xA = = 0.5 xB = = 0.5 nT nT nA = 0.5nT = 0.5CV nB = 0.5nT = 0.5CV kg MMixture = xA MA + xB MB = (0.5)(46) + (0.5)(18) = 32 kmole kg ρMixture = xA ρA + xB ρB = (0.5)(789) + (0.5)(1000) = 894.5 3 m kg 894.5 3 ρMixture kmole 1m3 kmole m C= = = 27.9531 × = 0.028 kg MMixture m3 1000L L 32 kmole kmole kmole nA = 0.5×0.028 ×10L nB = 0.5×0.028 ×10L L L Page - 124
nA = 0.14 kmole mA = 0.14 kmole×46
kg kmole
nB = 0.14 kmole mB = 0.14 kmole×18
kg kmole
mA = 6.44 kg mB = 2.52 kg ρA 𝑉𝐴 = 6.44 kg 𝜌𝐵 𝑉𝐵 = 2.52 kg 6.44 kg 2.52 kg 𝑉𝐴 = = 8.1622 𝐿 𝑉𝐵 = = 2.52 𝐿 3 kg kg 1𝑚 1𝑚3 789 3 × 1000𝐿 1000 3 × 1000𝐿 m m So, 8.1622 L of Ethanol and 2.52 L of Water are required for making 10 Liters of Mixture of 0.5, 0.5 Mole Fraction. 2) The equipment will be set up to operate at total reflux meaning all the formed vapor will after condensation return to the column. The charge of feed mixture can be loaded directly in the reboiler through the filler cap provided without first charging the feed tank. At total reflux, there will be no feed or top product or bottom product. 3) Before starting, make sure all valves on the equipment are closed. Open valve V10 on the reflux pipe. Fill the boiler with mixture to be distilled. Make sure the filler cap on the top of the reboiler is firmly replaced. 4) Turn on the power to the control panel. Set the temperature selector switch to T9, the temperature in the reboiler and open valve V5 admitting the cooling water to the condenser at a flow rate on FI1 of approximately 3 liters/ min. 5) On the control panel turn the power controller for the reboiler heating element fully anti-clockwise and switch on the power to the heating element to "power on" position. Another red lamp will illuminate indicating the heating element is on. 6) Turn the power controller clockwise until a reading of approximately 0.75kW is obtained on the digital wattmeter. The contents of the reboiler will begin to warm up and this can be observed on the temperature readout meter. 7) Open valves V6 and V7 which connect base and top of the distillation column, respectively, to the manometer. Initially there will be no pressure difference in the column meaning no reading on the manometer. 8) Close valve V6 and V7. The 1st and 5th plates in the column sections are not insulated so that observation of the sieve plates are possible. Eventually, vapor will begin to rise up the column and the progress of this can be clearly observed as well as detected by the increasing temperatures when switching the temperature selector on T8, T7, T6, T5, T4, T3, T2 and Tl. 9) Vapor will enter the condenser and reappear as droplets into the glass walled distillate receiver vessel. The distillate will build up a small level in the receiver and eventually overflow to the reflux regulator valve. Since the valve is not on (on the control pane!), and it will not be necessary to have it on in this experiment, which is run under total reflux, the condensate vapor will return to the column. 10) The cool distillate is then returning on the top of the column and will cascade down the trays forming a liquid level on the trays and bubbling of vapor passing through the liquid. The system will have reached an equilibrium condition when the temperatures Tl, T2, T3, T4, T5, T6, T7 and T8 are constant. 11) The boil-up rate can be measured by operating valve V3 so that all the condensate is diverted into a measuring cylinder and the time observed to collect a set quantity. This
Page - 125
will not disrupt the equilibrium conditions in the column provided a liquid level is maintained in the condensate feeding pipe. 12) When taking a sample, partially open valve V3 and drain the condensate (in a separate measuring cylinder) from the reflux system until a steady flow is obtained. (Ensure that liquid remains in the flexible connecting tube to prevent vapor from escaping.) 13) Start sample collection and timing at the same time. Collect a sizeable amount approximately 90 ml in a 100ml measuring cylinder. Pour the first non-representative collected amount in a bottle labelled "recyclable Ethanol / Water". 14) After taking the samples, take readings of pressure drops over both the rectifying (top) and the stripping (bottom) sections by opening the valves V6 and V7 on the manometer. 15) When opening the valves, make sure always to open valve V6 then V7 to prevent vapor from the column entering the manometer. If this happens, it can be seen as two separate phases in the U-tube. Close the valves in the same order, when finished the pressure drop reading. 16) Repeat these readings until two in a row agree fairly closely. Allow 5 to 10 minutes between each set of measurements before starting the next set in order for the system to reach equilibrium again. 17) Step up the boil-up rate in 250 Watt increments up to maximum 1.5 kW by adjusting the boiler heater power controller (on the control panel). Take-similar readings of the boil-up rate and pressure drops after having allowed at least 10 minutes to let the column stabilize.
Page - 126
Data Analysis: Power (kW) 0.50 0.75 1.00 1.25 1.50 1.75
Boil-up Rate (Liters/hr)
Pressure Drop (cm H2O)
Degree of Foaming on Trays
NOTE: The comment "Degree of Foaming on Trays" should be filled in using descriptive words e.g. None Gentle Localized Violent Localized Foaming Gently Over Whole Tray Foaming Violently Over Whole Tray Liquid Flooding in Column From the results, plot the curve relating pressure drop as a function of boil-up rate on log/log graph paper. Result obtained will be like this:
Relate the descriptive comments observed (and noted in the table of results) to zones on the curve.
Page - 127
Experiment 5 (BATCH DISTILLATION APPARATUS) Objective: Use of the refractometer for determining mixture compositions.
Equipment Setup / Apparatus: Batch Distillation Apparatus, Hand Held Refractometer, Measuring Cylinder 100ml Throughout the experimental procedures carried out on the Distillation Column, it is essential to have a convenient quick method of determining the composition of the binary mixture taken from the various sample points on the equipment. Such a method involves the use of a refractometer since the refractive index of these mixtures varies with composition. It is needed to have a suitable container to mix the sample in, and a bottle of each of the pure components of the binary mixture to be analyzed.
Reagents: Ethanol, Water
Theory: For the system, Ethanol / Water, mixtures of known concentration can be made up and their refractive indexes measured. The refractometer measures the critical angle of the liquid under test and each concentration will show a different critical angle Theta. Beyond the critical angle is darkness and refractometers are calibrated along this light/dark boundary.
Page - 128
Procedure: 1) Measure the refractive index (R.I.) of pure Ethanol and pure Water. 2) Make up small quantities of 25 mole percent, 50 mole percent and 75 mole percent Ethanol using the similar procedure as in previous experiment and measure their R.I. 3) Calculate the volume of constituents to use as in the previous experiment:
Data Analysis: Mole Fraction of Ethanol Refractive Index 1.00 0.75 0.50 0.25 0.00 Plot graph of refractive index versus mole fraction of methylcyclohexane in methylcyclohexane / toluene mixture. General trend of this graph is shown below.
For any mixture composition of these two constituents simply measure the refractive index y and read off the composition x.
Page - 129
Experiment 6 (BATCH DISTILLATION APPARATUS) Objective: To determine the overall column efficiency at varying boil-up rates.
Equipment Setup / Apparatus: Batch Distillation Apparatus, Hand Held Refractometer, Measuring Cylinder 250ml, Stop Watch.
Reagents: Ethanol, Water
Page - 130
Procedure: 1) Make 10 liters of a mixture of 50 mole percent Ethanol and 50 mole percent Water by using the steps of solution preparation of experiment 4. 2) The equipment will be set up to operate at total reflux so the charge of feed mixture can be loaded directly into the reboiler through the filler cap provided without first charging the feed tanks. At total reflux, there will be no feed or top product or bottom product. 3) Start up the unit, set the heat controller high at first then reduce heat; as reflux is introduced to give steady bubbling on all tray and total reflux. Leave the apparatus for at least 30 minutes so that the system can reach an equilibrium condition. 4) Measure the boil-up rate as described under experiment 4 using valve V3. Do this work three times and take an average value. Take a sample of the overheads through valve V3. When doing that, be careful never to drain the condensate return line i.e. partially open valve V3 to leave a small amount of liquid in the line all the time. 5) Generally, when taking samples, drain a "discarding" sample of approximately 5 to 10 ml before taking the representative sample in a small glass. Do not drain too much of the "discarding" sample because of the disturbance of the mass balance. Discard the "discarding" sample in safe way. After the representative sample, has been taken, keep the sample glasses in an upright position. Do not overturn them because of the possibility of evaporation of the sample. 6) Record the refractive index for the taken overhead sample. In a similar manner take a sample of the bottom through valve V2. CAUTION! THIS SAMPLE WILL BE HOT, (take note of T9). Record the refractive index for this sample, too. 7) Repeat this procedure every ten minutes until five samples of both overhead and bottom are obtained. Record the temperatures T8 and T1 to calculate the average column temperature. 8) Repeat this procedure for several different boil-up rates to cover over the operating range of the column. 9) The calibration graph developed in the previous Experiment 5 can be used to determine the concentrations of the components in the taken samples.
Data Analysis:
Boil-up rate = __________________ liters/hour. Overhead Concentration (XA)D = (Mole Percent Ethanol)
a) b) c) d) e) Average = ________________ mole percent of Ethanol. Bottom Concentration (XA)B =
a) b) c) Page - 131
d) e) Average Column Temperature (Top Side) =
___________ oC.
Average Column Temperature (Bottom Side) =
___________ oC.
Overall Average Colum Temperature =
___________ oC.
The curve shown in the next page shows: Vapor-Liquid Equilibrium Data of Ethanol / Water Mixtures
To calculate the number of theoretical plates for a given separation at total reflux. FENSKE’S METHOD Fenske developed the following formula: 𝑛+1=
𝑥 𝑥 log[(𝑥𝐴 )𝑑 ×( 𝑥𝐵 )𝑏 ] 𝐵
𝐴
log(𝛼𝐴𝐵 )𝑎𝑣
Where: Page - 132
𝑛 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑝𝑙𝑎𝑡𝑒𝑠 𝑥𝐴 = 𝑀𝑜𝑙𝑒 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝑀𝑜𝑟𝑒 𝑉𝑜𝑙𝑎𝑡𝑖𝑙𝑒 𝐶𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡 𝑥𝐵 = 𝑀𝑜𝑙𝑒 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝐿𝑒𝑠𝑠 𝑉𝑜𝑙𝑎𝑡𝑖𝑙𝑒 𝐶𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡 𝛼𝐴𝐵,𝑎𝑣 = 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑉𝑜𝑙𝑎𝑡𝑖𝑙𝑖𝑡𝑦 Subscripts D, B indicate distillate and bottom respectively. 𝛼𝐴𝐵,𝑎𝑣 = √𝛼𝐷 . 𝛼𝐵 The efficiency is given by: 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 = 𝐸 =
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑃𝑙𝑎𝑡𝑒𝑠 ×100 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝐴𝑐𝑡𝑢𝑎𝑙 𝑃𝑙𝑎𝑡𝑒𝑠
Knowing the composition of distillate and bottom and the corresponding volatilities, the column efficiency can be determined.
Page - 133
Experiment 7 (CONTINUOUS DISTILLATION APPARATUS) Objective: Steady state distillation of a binary mixture under continuous operation.
Equipment Setup / Apparatus: Continuous Distillation Apparatus, Hand Held Refractometer, Measuring Cylinder 250ml, Stop Watch.
Reagents: Ethanol, Water
Page - 134
Theory: Calculation of Number of Plates using McCabe Thiele Method. Rectifying Section Operating Line
Stripping Section Operating Line
Page - 135
Above equations combined with the equilibrium curve can be used to calculate the composition on the various plates working from the condenser down to the still. The plate which has a composition nearest to that of the feed should, be used as the feed plate. Consequently, the number of theoretical plates and position of entry for the feed can be calculated.
Procedure: 1) Charge 10 liters feed mixture of 65 mole percent Ethanol and 35 mole percent Water to feed tank. Volume of individual components required can be calculated from a procedure similar to experiment no-4: 2) Charge the reboiler with 10 liters of a mixture of 25 mole percent Ethanol and 75 mole percent Water. Volume of individual components required can be calculated from a procedure similar to experiment no-4: 3) Make sure the filler cap on the top of the reboiler is firmly placed. Turn on the power to the control panel. Set the temperature selector switch to T9, that is the temperature in the reboiler, and open valve V5 admitting the cooling water to the condenser at a flow rate on FI1 of approximately 3 liters/min. This rate may be varied according to the temperature of the water. 4) On the control panel turn the power controller for the reboiler heating element fully anti-clockwise and turn on the power to the heating element. Another red lamp will illuminate indicating the heating element is on. Turn the power controller clockwise until a reading of approximately 1.5 kW is obtained on the digital wattmeter. The contents of the reboiler will begin to warm up and this can be observed on the temperature readout, meter. 5) Eventually, vapor will begin to rise up the column and the progress of this can be clearly observed as well as detected by the increasing temperatures when switching the temperature selector on T8, T7, T6, T5, T4, T3, T2 and Tl. Vapor will enter the condenser and reappear as droplets into the glass walled distillate receiver vessel. The distillate will build up a small level in the receiver and eventually overflow to the reflux regulator valve. Start the experiment with total reflux, meaning the condensed vapor will return to the column.
Page - 136
6) The cool distillate is then returning to the top of the column and will cascade down the trays forming a liquid level on the trays and bubbling of vapor passing through the liquid. The system will have reached an equilibrium condition when the temperatures Tl, T2, T3, T4, T5, T6, T7 and T8 have reached an average steady temperature (but note cycling due to the intermittent reflux). 7) Before switching on the reflux switch, set the reflux ratio to 5:1, meaning 5 sec back to column and 1 sec to top product receiver. 8) The feed to the column must be admitted on the tray 5. When the column has stabilized at total reflux (it Takes 15 to 30 minutes), the flow of feed and the reflux can be started at the same time. It is advisable to set a feed flow of 2 liters/hr (from the feed pump calibration graph). As the flow into the column becomes established so more vapor will rise up the column and appear as condensate in the distillate receiver, allow this to flow to the top product receiver. 9) After feeding approximately 3 liters take a sample of the overheads through valve V3. When doing that, be careful never to drain the condensate return line i.e. partially open valve V3 to leave a small amount of liquid in the line all the time. Take a further four samples. 10) Generally, when taking samples, drain a "discarding" sample of approximately 5 to 10 ml before taking the representative sample in a sample glass. Do not drain too much of the "discarding" sample because of the disturbance of the mass balance. Discard the "discarding" sample in a safe way. After the representative sample, has been taken, keep the sample glasses in an upright position. Do not overturn them because of the possibility of evaporation of the sample. 11) Record the refractive index for the taken overhead sample. In a similar manner and preferably at the same time take a sample of the bottom through valve V2. CAUTION! THIS SAMPLE WILL BE HOT. Record the refractive index for this sample, too. 12) Repeat the sample taking a further nine times during the experiment (before feed runs out).
Page - 137
Data Analysis:
Sr. No.
Top Product Composition (Mole Bottom Product Composition (Mole Fraction of Ethanol) Fraction of Ethanol)
1 2 3 4 5 6 7 8 9 10 Equilibrium Data for Ethanol / Water can be calculated using Vapor Liquid Equilibrium Curve for this system at 1 atm pressure.
Sample Results: Using a feed of a binary mixture of 60 mole percent Ethanol and 40 mole percent Water. Top product required: XD = 0.75 Bottom product required: XB = 0.44 Reflux Ratio: 5:1 A material balance on the M.V.C. (More Volatile Component), Ethanol gives: Units are of molar flow rates: F=D+B 100 × 0.60 = 0.75 D + 0.44 B And D = 100-B 100×0.60 = 0.75(100-B) + 0.44B B = 48.39 D = 51.61 Ln = 5D Ln = 258.05 Page - 138
V(n+1) = Ln + D V(n+1) = 309.66 𝑦𝑛+1 = 𝑦𝑛+1 =
𝐿𝑛 𝐷 𝑥𝑛 + 𝑥 𝑉𝑛+1 𝑉𝑛+1 𝐷
258.05 51.61×0.75 𝑥𝑛 + 309.66 309.66
𝑦𝑛+1 = 0.83𝑥𝑛 + 0.13 L (bar) = 258.05 + 100 = 358.05 V (bar) = L (bar) – B = 358.05 -48.39 = 309.66 𝑦𝑚+1 = 𝑦𝑚+1 =
𝐿̅ 𝐵 𝑥𝑚 − 𝑥𝐵 𝑉̅ 𝑉̅
358.05 48.39×0.44 𝑥𝑚 − 309.66 309.66
𝑦𝑚+1 = 1.16𝑥𝑚 − 0.07 From the equilibrium curve, 1) Use Equilibrium Curve, and plot specific top and bottom operating line equations on the same diagram. 2) Calculate number of stages:
Page - 139
3) Theoretically, therefore, the distillation column containing eight sieve plates plus the boiler will give the compositions calculated above. However, as the experiment will show this is not in fact correct. 4) Determine average column efficiency.
Page - 140
Experiment 8 (CONTINUOUS DISTILLATION APPARATUS) Objective: Effect of varying the feed position under continuous operation.
Equipment Setup / Apparatus: Continuous Distillation Apparatus, Hand Held Refractometer, Measuring Cylinder 250ml, Stop Watch.
Reagents: Ethanol, Water
Page - 141
Theory: The rig is provided with three feed positions, one above the top plate, one between the two four-plate sections, (mid-point) and one below the bottom plate. In this way, the rig can be run as a conventional distillation column (feed between the sections), as a rectifying column (feed below the bottom plate) or as a stripping column (feed above the top plate). As the rectifying case is closely approximated, by the batch distillation. The stripping case is chosen for this experiment.
Calculation of Number of Plates using McCabe Thiele Method.
Material Balance of top of the column 𝑉𝑛 = 𝐿𝑛+1 + 𝐷 − 𝐹 With respect to M.V.C. this becomes 𝑉𝑛 𝑦𝑛 = 𝐿𝑛+1 𝑥𝑛+1 + 𝐷𝑥𝐷 − 𝐹𝑥𝐹 𝐿𝑛+1 𝑥𝑛+1 𝐷𝑥𝐷 𝐹𝑥𝐹 𝑦𝑛 = + − 𝑉𝑛 𝑉𝑛 𝑉𝑛 Since the liquid overflow is constant Ln = Ln+1 𝐿𝑛 𝑥𝑛+1 𝐷𝑥𝐷 𝐹𝑥𝐹 𝑦𝑛 = + − 𝑉𝑛 𝑉𝑛 𝑉𝑛
Material Balance of bottom of the column: Vm = Lm+1 - W With respect to M.V.C. this becomes 𝑉𝑚 𝑦𝑚 = 𝐿𝑚+1 𝑥𝑚+1 − 𝑊𝑥𝐵 Page - 142
𝑦𝑚 =
𝐿𝑚+1 𝑥𝑚+1 𝑊𝑥𝐵 − 𝑉𝑚 𝑉𝑚
Since the liquid overflow is constant Lm = Lm+1. As the feed is introduced in the top of the column Lm = Ln and also Vm = Vn. Above equations combined with the equilibrium curve can be used to calculate the composition on the various plates working from the condenser down to the still.
Procedure: 1) Charge 10 liters feed mixture of 63 mole percent Ethanol and 37 mole percent Water to feed tank. Volume of individual components required can be calculated from a procedure similar to experiment no-4: 2) Charge the reboiler with 10 liters of a mixture of 25 mole percent Ethanol and 75 mole percent Water to overflow valve V1. Volume of individual components required can be calculated from a procedure similar to experiment no-4: 3) Make sure the filler cap on the top of the reboiler is firmly placed. Turn on the power to the control panel. Set the temperature selector switch to T9, that is the temperature in the reboiler, and open valve V5 admitting the cooling water to the condenser at a flow rate on FI1 of approximately 3 liters/min. This rate may be varied according to the temperature of the water. 4) On the control panel turn the power controller for the reboiler heating element fully anti-clockwise and turn on the power to the heating element. Another red lamp will illuminate indicating the heating element is on. Turn the power controller clockwise until a reading of approximately 1.5 kW is obtained on the digital wattmeter. The contents of the reboiler will begin to warm up and this can be observed on the temperature readout, meter. 5) Eventually, vapor will begin to rise up the column and the progress of this can be clearly observed as well as detected by the increasing temperatures when switching the temperature selector on T8, T7, T6, T5, T4, T3, T2 and Tl. Vapor will enter the condenser and reappear as droplets into the glass walled distillate receiver vessel. The distillate will build up a small level in the receiver and eventually overflow to the reflux regulator valve. Start the experiment with total reflux, meaning the condensed vapor will return to the column. Page - 143
6) The cool distillate is then returning to the top of the column and will cascade down the trays forming a liquid level on the trays and bubbling of vapor passing through the liquid. The system will have reached an equilibrium condition when the temperatures Tl, T2, T3, T4, T5, T6, T7 and T8 have reached an average steady temperature (but note cycling due to the intermittent reflux). 7) Before switching on the reflux switch, set the reflux ratio to 5:1, meaning 5 sec back to column and 1 sec to top product receiver. 8) The feed to the column must be admitted above the top plate. When the column has stabilized at total reflux (it Takes 15 to 30 minutes), the flow of feed and the reflux can be started at the same time. It is advisable to set a feed flow of 2 liters/hr (from the feed pump calibration graph). As the flow into the column becomes established so more vapor will rise up the column and appear as condensate in the distillate receiver, allow this to flow to the top product receiver. 9) After feeding approximately 3 liters take a sample of the overheads through valve V3. When doing that, be careful never to drain the condensate return line i.e. partially open valve V3 to leave a small amount of liquid in the line all the time. Take a further four samples. 10) Generally, when taking samples, drain a "discarding" sample of approximately 5 to 10 ml before taking the representative sample in a sample glass. Do not drain too much of the "discarding" sample because of the disturbance of the mass balance. Discard the "discarding" sample in a safe way. After the representative sample, has been taken, keep the sample glasses in an upright position. Do not overturn them because of the possibility of evaporation of the sample. 11) Record the refractive index for the taken overhead sample. In a similar manner and preferably at the same time take a sample of the bottom through valve V2. CAUTION! THIS SAMPLE WILL BE HOT. Record the refractive index for this sample, too. 12) Repeat the sample taking a further nine times during the experiment (before feed runs out).
Page - 144
Data Analysis:
Sr. No.
Top Product Composition (Mole Bottom Product Composition (Mole Fraction of Ethanol) Fraction of Ethanol)
1 2 3 4 5 6 7 8 9 10 Equilibrium Data for Ethanol / Water can be calculated using Vapor Liquid Equilibrium Curve for this system at 1 atm pressure.
Sample Results: Using a feed of a binary mixture of 63 mole percent Ethanol and 47 mole percent Water. Top product required: XD = 0.66 Bottom product required: XB = 0.21 Reflux Ratio: 5:1 A material balance on the M.V.C. (More Volatile Component), Ethanol gives: Units are of molar flow rates: F=D+B 100 × 0.63 = 0.66 D + 0.21 B And D = 100-B 100×0.63 = 0.66(100-B) + 0.21B B = 6.67 D = 93.33 Also Ln = 5D Ln = 466.65 Vn = Ln + D – F = 466.65 + 93.33 - 100 Vn = 459.98 Page - 145
𝑦𝑛 = 𝑦𝑛 =
𝐿𝑛 𝐷 𝐹 𝑥𝑛+1 + 𝑥𝐷 − 𝑥𝐹 𝑉𝑛 𝑉𝑛 𝑉𝑛
466.65 93.33×0.66 100×0.63 𝑥𝑛+1 + − 499.98 499.98 499.98 𝑦𝑛 = 0.933𝑥𝑛+1 − 0.003
It is for the top section and the bottom section of the column due to different feed position. From the equilibrium curve, 1) Use Equilibrium Curve, and plot specific operating line equation on the same diagram. 2) Calculate number of stages: 3) Theoretically, therefore, the distillation column containing eight sieve plates plus the boiler will give the compositions calculated above. However, as the experiment will show this is not in fact correct. 4) Determine average column efficiency.
Page - 146
Experiment 9 (GAS ABSORPTION COLUMN APPARATUS) Objective: To measure the absorption of carbon dioxide into water flowing down the tower, using the gas analysis equipment provided.
Equipment Setup / Apparatus: Gas Absorption Column Apparatus, CO2 Cylinder with Integral Pressure Regulator, Small Funnel, and Tubing.
Reagents: CO2 Gas, Tap Water, Air, and 300ml of 1.0 molar NaOH solution.
Page - 147
Procedure: 1) First fill the two globes of the absorption analysis equipment on the left of the panel with 1.0 Molar NaOH solution. Adjust the level in the globes to the '0' mark on the sight tube, using drain valve C into a flask to do this. 2) Fill the liquid reservoir tank to three-quarters full with fresh tap water. 3) With gas flow control valves C2 and C3 closed, start the liquid pump and adjust the water flow through the column to approximately 6 liters/minute on flowmeter F1 by adjusting control valve C1. 4) Start the compressor and adjust control valve C2 to give an air flow of approximately 30 liters/minute in flowmeter F2. 5) Carefully open the pressure regulating valve on the carbon dioxide cylinder, and adjust valve C3 to give a value on the flowmeter F3 approximately one half of the air flow F2. (Ensure the liquid seal at the of base of the absorption column is maintained by, if necessary, adjustment of control valve C4. 6) After 15 minutes or so of steady operation, take samples of gas simultaneously from sample points S1 and S2. Analyze these consecutively for carbon dioxide content in these gas samples. 7) Flush the sample lines by repeated sucking from the line, using the gas piston and expelling the contents of the cylinder to atmosphere. Note that the volume of the cylinder is about l00 cm3. Estimate the volume of the tube leading to the device. Then decide how many times you need to suck and expel. (Steps B and C) 8) With the absorption globe, isolated and the vent to atmosphere closed, fill the cylinder from the selected line by drawing the piston out slowly (Step B). Note volume taken into cylinder V1, which should be approximately 20ml for this particular experiment. Wait at least two minutes to allow the gas to come to the temperature of the cylinder. 9) Isolate the cylinder from the column and the absorption globe and vent the cylinder to atmospheric pressure. Close after about 10 seconds (Step D). 10) Connect cylinder to absorption globe. The liquid level should not change. If it does change, briefly open to atmosphere again. 11) Wait until the level in the indicator tube is on zero showing that the pressure in the cylinder is atmospheric. 12) Slowly close the piston to empty the cylinder into the absorption globe. Slowly draw the piston out again (Steps E and F). Note the level in the indicator tube. Repeat steps Page - 148
E and F until no significant change in level occurs. Read the indicator tube marking = V2. This represents the volume of the gas sampled.
HEMPL APPARATUS FOR GAS ANALYSIS
Page - 149
WARNING: If the concentration of CO2 in the gas sampled is greater than 8%, it is possible to suck liquid into the cylinder. This will ruin your experiment and takes time to correct. Under these circumstances, do not pull the piston out to the end of its travel. Stop it at a particular mark, e.g. V1 = 20 on the coarse scale, and read the fine scale.
Data Analysis:
NOTATION: V1 = Volume of Gas sample taken in Hempl Apparatus (ml). V2 = Corresponds to amount of Gas Absorbed in Hempl Apparatus (ml). F = Volumetric Flowrate (liters/sec). G = Gas Flowrate (gmols/sec). Y = Mole Fraction of component in gas phase.
SUBSCRIPTS: T = Total i = Inlet Conditions to Column o = Outlet Conditions from Column
CO2 content of gas samples: From use of Hempl Apparatus, 𝑉𝑜𝑙𝑢𝑚𝑒 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑂2 =
𝑉2 𝑉1
For ideal gases, volume fraction = mole fraction = Y. Check that the sample taken from the inlet to the absorption column should give the same value of CO2 fraction as that indicated by the inlet flowmeters:
𝑌𝑖 =
𝑉2 𝐹3 = 𝑉1 𝐹2 + 𝐹3
Page - 150
READINGS AT INLET F3
F2
(CO2)
(Air)
Liters/sec
Liters/sec
From Flowmeters
CALCULATIONS
V1
V2
ml
ml
𝑌𝑖 =
𝐹3 𝐹2 + 𝐹3
𝑌𝑖 =
𝑉2 𝑉1
From Hempl Apparatus and Sample Point S3
Calculation of amount of CO2 absorbed in column from analysis of samples at inlet and outlet. From Analysis with Hempl apparatus, volume fraction of CO2 in gas stream at inlet: 𝑉2 𝑌𝑖 = ( ) 𝑉1 𝑖 And at outlet: 𝑉2 𝑌𝑜 = ( ) 𝑉1 𝑜 If Fa is liters/second of CO2 absorbed between top and bottom, then:
CO2 IN
CO2 OUT
CO2 Absorbed
[𝐹2 + 𝐹3 ]𝑌𝑖 − [𝐹2 + (𝐹3 − 𝐹𝑎 )]𝑌𝑜 = 𝐹𝑎
𝐹𝑎 =
(𝑌𝑖 − 𝑌𝑜 )(𝐹2 + 𝐹3 ) (𝑌𝑖 − 𝑌𝑜 ) = ×(𝑇𝑜𝑡𝑎𝑙 𝐺𝑎𝑠 𝐼𝑛𝑙𝑒𝑡 𝐹𝑙𝑜𝑤) (1 − 𝑌0 ) 1 − 𝑌𝑜 INLET CONDITIONS
GAS FLOWS [liters/sec] Air
CO2
Total
F2
F3
F2+F3
OUTLET GAS
GAS
SAMPLE
SAMPLE
𝑉2 𝑌𝑖 = ( ) 𝑉1 𝑖
𝑉2 𝑌𝑜 = ( ) 𝑉1 𝑜
ABSORBED CO2: Fa [liters/sec]
Note: [Liters/second] can be converted to [gmols/second] as follows: 𝐺𝑎 =
𝐹𝑎 𝐴𝑣𝑔. 𝑐𝑜𝑙𝑢𝑚𝑛 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑚𝑚 𝐻𝑔 273 ×( )×( ) 22.42 760 𝐴𝑣𝑔. 𝑐𝑜𝑙𝑢𝑚𝑛 𝑡𝑒𝑚𝑝. 0𝐶 + 273
Absorbed CO2 Fa = ___________________ Page - 151
Ga = _______________________________
The assumption implicitly made here is that the volume flow is not affected by the pressure drop through the column as this drop should be small in comparison with atmospheric pressure.
Page - 152
Experiment 10 (GAS ABSORPTION COLUMN APPARATUS) Objective: To calculate rate of absorption of CO2 into water from analysis of liquid solutions flowing down absorption column.
Equipment Setup / Apparatus: Gas Absorption Column Apparatus, CO2 Cylinder with Integral Pressure Regulator, and Pyrex Bottle, Pipette, Burette, Flask and Measuring Cylinder.
Reagents: CO2 Gas, Water, Air, Phenolphthalein, 0.0277 Molar NaOH Solution, 0.01 Molar NaHCO3 Solution.
Page - 153
Procedure: 1) Fill the liquid reservoir tank at the base of the column to approximately three-quarters full with (preferably) deionized water. Note the volume added [VT liters]. 2) With gas flow control valves C2 and C3 closed, start the liquid pump and adjust the water flow through the column to approx. 6 liters/minute on flowmeter F1 by adjusting flow control valve C1. 3) Start the compressor and adjust control valve C2 to give an air flow of approx. 10% of full scale on flowmeter F2. 4) Carefully open the pressure regulating valve on the carbon dioxide cylinder, and adjust valve C3 to give a value on the flowmeter F3 approx., one half of the air flow F2 ensure the liquid seal at the base of the absorption column is maintained by, if necessary adjustment of control valve C4. 5) After 15 minutes of steady operation, take samples at 10 minute intervals from S4 and S5. Take 150ml samples at known times in each case. Analyze the samples according to the procedure detailed below.
Analysis of Carbon Dioxide Dissolved in Water: Note: Water used for absorption should be deionized as presence of dissolved salts affect the analysis described below. If tap water is used, no metal ions should be present in greater quantities than 1.0 mg/liter and pH should be just alkaline: 7.1 to 7.8. 1) Phenolphthalein indicator prepared from carbon dioxide – free distilled water. 2) Standard 0.0277M NaOH solution, prepared by diluting 27.70ml of 1M NaOH standard solution to1 liter with carbon dioxide free distilled water. Prepare fresh and protect from carbon dioxide in the atmosphere by keeping in a stoppered Pyrex bottle. 3) Standard 0.01M NaHCO3 solution, prepared by dissolving approximately 0.1 gram of anhydrous NaHCO3 in carbon dioxide free distilled water to 100ml. 4) Withdraw a sample of liquid S5 from the sump tank with the sampler provided, approximate volume of 150ml, or from liquid outflow point S4. 5) Discharge the sample at the base of a 100 ml graduated cylinder, flicking the cylinder to throw off excess liquid above the 100 ml mark. 6) Add 5-10 drops of phenolphthalein indicator solution if the sample turns red immediately, no free C02 is present. If the sample remains colorless, titrate with
Page - 154
standard NaOH solution. Stir gently with a glass rod until a definite pink color persists for about 30 seconds. This color change is the end point - note volume VB of NaOH solution added. For best results, use a color comparison standard, prepared by adding the identical volume of phenolphthalein solution to 100ml of sodium bicarbonate solution in a similar graduated cylinder.
Data Analysis:
NOTATION: Cd = Concentration of dissolved free carbon dioxide (gmol/liter). F = Volumetric Flowrate (liters/sec). VB = Volume of NaOH Solution Added in liquid analysis (ml).
SUBSCRIPTS: T = Total i = Inlet Conditions to Column o = Outlet Conditions from Column
The amount of free CO2 in the water sample is calculated from: 𝐶𝑑 =
𝑔𝑚𝑜𝑙 𝑉𝐵 ×0.0277 𝑜𝑓 𝑓𝑟𝑒𝑒 𝐶𝑂2 = 𝑙𝑖𝑡𝑒𝑟 𝑚𝑙. 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒
Note: Solubility of CO2 in water is a strong function of temperature. And the accuracy of this titrimetric method is approximately ±10%.
F1 = _________________ liters/sec. VT = _________________ Volume of Water in System (liters).
Page - 155
From Sump Tank S5 (Correspond to conditions at top of
S4
tower)
Time from Start (minutes)
From Liquid Outlet Sample Point
VB ml
Cd in tank [Cdi] gmol/liter
VB ml
Cd at outlet [Cdo] gmol/liter
10 20 30 40 50 60
CO2 absorbed over a time period (e.g. 30 minutes): 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑅𝑎𝑡𝑒 =
[𝐶𝑑𝑖 𝑎𝑡(𝑡 = 40) − 𝐶𝑑𝑖 𝑎𝑡(𝑡 = 10)]×𝑉𝑇 𝑔𝑚𝑜𝑙/𝑠𝑒𝑐 30×60
CO2 absorbed across the column at any particular time: Inlet flow of dissolved CO2 = F1×Cdi gmol/sec. = _____________________ gmol/sec. Outlet flow of dissolved CO2 = F1×Cdo gmol/sec. = ____________________ gmol/sec. 𝐴𝑏𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 = 𝐹1 [𝐶𝑑𝑖 − 𝐶𝑑𝑜 ] 𝑔𝑚𝑜𝑙/𝑠𝑒𝑐
Page - 156
Experiment 11 (LIQUID-LIQUID EXTRACTION APPARATUS) Objective: To determine the Distribution Coefficient for the system Trichloroethylene – Propanoic Acid – Water and to show its dependence on concentration.
Equipment Setup / Apparatus: 250ml Conical Stoppered Flask or Beaker, 250ml Measuring Cylinder, 250ml Separating Funnel, Pipette with Rubber Bulb, Burette, and Funnel.
Reagents: 0.1 Molar NaOH Solution, Phenolphthalein, Propionic Acid, Trichloroethylene, Water.
WARNING: Concentrated Sodium Hydroxide can form explosive volatile products when in contact with Trichloroethylene. Ensure that diluted Sodium Hydroxide (NaOH) is used when performing this experiment.
Page - 157
Theory: The solvent (water) and solution (trichloroethylene/propionic acid) are mixed together and then allowed to separate into the extract phase and the raffinate phase. The extract phase will be water and propionic acid and the raffinate phase is trichloroethylene with a trace of propionic acid. The Distribution Coefficient K, is defined as the ratio: 𝐾=
𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑒𝑥𝑡𝑟𝑎𝑐𝑡 𝑝ℎ𝑎𝑠𝑒 𝑌 = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑟𝑎𝑓𝑓𝑖𝑛𝑎𝑡𝑒 𝑝ℎ𝑎𝑠𝑒 𝑋
It is assumed that phase equilibrium exists between the two phases. At low concentrations, the distribution coefficient is dependent on the concentration and thus Y = KX.
Procedure: 1) Make up in a conical flask a mixture of 50ml trichloroethylene and 50ml of demineralized water. 2) Add 5ml of propionic acid. 5ml can be pipetted into the flask using a pipette with a rubber bulb. 3) Place a stopper into the flask and shake for a minimum of 5 minutes. 4) Pour into a separating funnel, leave for 5 minutes and remove the lower aqueous layer. 5) Take a 10ml sample of this layer and titrate against 0.1M NaOH solution using phenolphthalein as an indicator. 6) Repeat the experiment for two further concentrations of propionic acid i.e. for initial additions of 3ml and 1ml of propionic acid.
Data Analysis:
Volume of Propionic Acid
0.1M NaOH
Added (ml)
Solution used. (ml)
Propionic Acid
Propionic Acid
Concentration
Concentration
in Aqueous
in Organic
Layer
Layer
Y
X
Distribution Coefficient 𝐾=
𝑌 𝑋
5 3 1 Page - 158
Page - 159
Experiment 12 (LIQUID-LIQUID EXTRACTION APPARATUS) Objective: To demonstrate how a mass balance is performed on the extraction column, and to measure the mass transfer coefficient and its variation with flowrate with the aqueous phase as the continuous medium.
Equipment Setup / Apparatus: Liquid-Liquid Extraction Apparatus, 250ml Conical Stoppered Flask, 250ml Measuring Cylinder, Pipette with Rubber Bulb, Burette.
The solvent metering pump is calibrated in percentage of maximum flow which varies slightly from pump to pump. The pump should be calibrated initially by setting F2 to 100%, setting valve V8 to the calibrate position and measuring the flow from the pump, using a measuring cylinder and stopwatch. Calculate the flow rate produced settings of 10% intervals (ml per minute), then plot a graph of ml per minute against percentage of metering pump stroke. Thereafter any selected flow may be obtained by using the graph.
Page - 160
Reagents: 0.1 Molar NaOH Solution, Phenolphthalein, Propionic Acid, Trichloroethylene, Water.
Procedure:
WARNING: Concentrated Sodium Hydroxide can form explosive volatile products when in contact with Trichloroethylene. Ensure that diluted Sodium Hydroxide (NaOH) is used when performing this experiment.
1) Add 100ml of propionic acid to 10 liters of trichloroethylene. Mix well to ensure an even concentration then fill the organic phase feed tank (bottom tank) with the mixture. 2) Switch the level control to the bottom of the column (electrode switch S2). Page - 161
3) Fill the water feed tank with 15 liters of clean de-mineralized water, start the water feed pump and fill the column with water at a high flow rate. 4) As soon as the water is above the top of the packing, reduce the flow rate to 0.2 liters/min. 5) Start the metering pump and set at a flow rate of 0.2 liters/min. 6) Run for 15-20 minutes until steady conditions are achieved, monitor flow rates during this period to ensure that they remain constant. 7) Take 15ml samples from the feed, raffinate and extract streams. 8) Titrate 10ml of each sample against 0.1M NaOH using phenolphthalein as the indicator. (To titrate the feed and raffinate they may need continuous stirring using a magnetic stirrer). 9) Repeat the experiment with both the water and trichloroethylene flow rates being increased to 0.3 1iters/min.
Data Analysis: NOTATION: Vw = Water flowrate (Liters/sec) V0 = Trichloroethylene flowrate (Liters/sec) X = Propionic acid concentration in the organic phase (kg/liter) Y = Propionic Acid concentration in the aqueous phase (kg/1iter) SUBSCRIPTS: 1 = Top of Column 2 = Bottom of Column
The equations are given for the system Trichloroethylene-Propionic Acid-Water. Propionic acid extracted from the organic phase (raffinate) = 𝑉𝑜 (𝑋1 − 𝑋2 ) Propionic acid extracted by the aqueous phase (extract) = 𝑉𝑤 (𝑌1 − 0) Therefore: 𝑉𝑜 (𝑋1 − 𝑋2 ) = 𝑉𝑤 (𝑌1 − 0) Mass transfer coefficient (based on the raffinate phase) kD: 𝑘𝐷 =
𝑅𝑎𝑡𝑒 𝑜𝑓 𝐴𝑐𝑖𝑑 𝑇𝑟𝑎𝑛𝑠𝑓𝑒𝑟 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑃𝑎𝑐𝑘𝑖𝑛𝑔 × 𝐿𝑜𝑔 𝑀𝑒𝑎𝑛 𝐷𝑟𝑖𝑣𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒
Page - 162
𝐿𝑜𝑔 𝑀𝑒𝑎𝑛 𝐷𝑟𝑖𝑣𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 =
∆𝑥1 − ∆𝑥2 ∆𝑥 𝑙𝑛 (∆𝑥1 ) 2
Where: ∆𝑥1 = 𝐷𝑟𝑖𝑣𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 𝑎𝑡 𝑡ℎ𝑒 𝑡𝑜𝑝 𝑜𝑓 𝑡ℎ𝑒 𝑐𝑜𝑙𝑢𝑚𝑛 = (𝑋2 − 0) ∆𝑥2 = 𝐷𝑟𝑖𝑣𝑖𝑛𝑔 𝐹𝑜𝑟𝑐𝑒 𝑎𝑡 𝑡ℎ𝑒 𝑏𝑜𝑡𝑡𝑜𝑚 𝑜𝑓 𝑡ℎ𝑒 𝑐𝑜𝑙𝑢𝑚𝑛 = (𝑋1 − 𝑋1∗ ) 𝑋1∗ = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑡ℎ𝑒 𝑜𝑟𝑔𝑎𝑛𝑖𝑐 𝑝ℎ𝑎𝑠𝑒 𝑤ℎ𝑖𝑐ℎ 𝑤𝑜𝑢𝑙𝑑 𝑏𝑒 𝑖𝑛 𝑒𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 𝑤𝑖𝑡ℎ 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑌1 𝑖𝑛 𝑡ℎ𝑒 𝑎𝑞𝑢𝑒𝑜𝑢𝑠 𝑝ℎ𝑎𝑠𝑒. The equilibrium values can be found using the distribution coefficient found in the previous experiment.
Flowrate of Aqueous Phase: Flowrate of Organic Phase: Volume of 0.1M NaOH
Concentration of Propionic
solution used in titration
Acid
(ml)
kg/liters
Feed: Raffinate: Extract: Propionic acid extracted from the organic phase: Propionic acid extracted from the aqueous phase: Mass Transfer Coefficient kD
Page - 163
Experiment 13 (TRAY DRIER APPARATUS) Objective: To produce drying and drying rate curves for a wet solid being dried with air of fixed temperature and humidity.
Equipment Setup / Apparatus: Tray Drier Apparatus, Digital Weight Balance, Wet and Dry Bulb Thermometer, and Stop Watch.
Reagents: Sand, Air.
Theory: Immediately after contact between the wet solid and the drying medium, the solid temperature adjusts until it reaches a steady state. The solid temperature and the rate of drying may increase or decrease to reach the steady state condition. At steady state, the temperature of the wet solid surface is the wet bulb temperature of the drying medium. Temperatures within Page - 164
the drying solid also tend to equal the wet bulb temperature of the gas but lag in movement of mass and heat in some deviation. Once the stock temperatures reach the wet bulb temperature of the gas, they are quite stable and the drying rate also remains constant. This is the constant rate drying period which ends when the solid reaches the critical moisture content. Beyond this point the surface temperature rises, and the drying rate falls off rapidly. The falling rate period can take a far longer time than the constant rate period even though the moisture removal may be less. The drying rate approaches zero at some equilibrium moisture content which is the lowest moisture content obtainable with the solid under the drying conditions used.
Procedure: 1) Take dry sand to fill the four trays to a depth of about 10 mm each should be accurately weighed before being saturated with water in a container. 2) The sand should be removed from the container and drained of excess “free” water before being loaded evenly and smoothly into the sand drying trays, taking care to avoid any spillage. 3) The total weight of the wet sand should be noted before drying commence. 4) At some arbitrary time (t=0), switch on and set the fan speed control to mid-position and the heater power control to maximum letting them remain constant throughout the experiment. 5) Record the total weight of sand in the trays at regular time intervals until drying is complete. NOTE: It is recommended that the laboratory be well ventilated to ensure that warm moist air discharged from the drier does not affect the original inlet conditions over the period of the experiment.
Data Analysis: Weight of dry sand = ________________ kg. XE = Equilibrium Moisture Content Time (min)
0
Weight of wet sand (kg) Moisture Content XE
Page - 165
𝑋𝐸 =
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐿𝑖𝑞𝑢𝑖𝑑 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑊𝑒𝑡 𝑆𝑎𝑛𝑑 − 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑
From the results, plot the drying curve relating moisture content as a function of time. Carefully differentiate data from this curve to produce the drying rate - moisture content plot, attempting to identify the points (A, B, C and D) at which the drying passes from one regime to the next.
Comment upon the results obtained and relate the curves to the mechanism by which drying occurs. What is the significance of the equilibrium moisture content?
Page - 166
Experiment 14 (TRAY DRIER APPARATUS) Objective: To investigate the influence of air temperature on the drying rate of a wet solid in air at fixed velocity.
Equipment Setup / Apparatus: Tray Drier Apparatus, Digital Weight Balance, Wet and Dry Bulb Thermometer, and Stop Watch.
Reagents: Sand, Air.
Procedure: 1) Take dry sand to fill the four trays to a depth of about 10 mm each should be accurately weighed before being saturated with water in a container. 2) The sand should be removed from the container and drained of excess 'free' water before being loaded evenly and smoothly into the drying trays, taking care to avoid any spillage. 3) The total weight of the wet sand should be noted before drying commences. Page - 167
4) At some arbitrary time (t=0), switch on and set the fan speed control to produce an air velocity of about 0.5 m/s, Measure the velocity of the air flow through the drier using the digital anemometer. 5) Set the heater power control to a nominal setting and measure the dry and wet bulb air temperatures upstream of the sand trays using the aspirating psychrometer. 6) Record the total weight of sand in the trays at regular time intervals until drying is complete. 7) The experiment should be repeated for other air temperatures by increasing the power supplied to the heater up to the maximum setting. 8) It is important to keep the air velocity constant and to use the same weight and distribution of sand in each of the tests.
NOTE: It is recommended that the laboratory be well ventilated to ensure that moist air discharged from the drier does not affect the original inlet conditions over the period of the experiments.
Data Analysis: The drying rate of a wet solid in air changes throughout the drying period since the controlling factors are different for each major section of the drying rate curve. However, many wet solids exhibit a period during which the drying rate is essentially constant and: 𝑅𝑐 ∝ ℎ𝑣 (𝑇𝑣 − 𝑇𝑖 ) Where: 𝑅𝑐 = 𝐷𝑟𝑦𝑖𝑛𝑔 𝑅𝑎𝑡𝑒 𝑑𝑢𝑟𝑖𝑛𝑔 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑟𝑎𝑡𝑒 𝑝𝑒𝑟𝑖𝑜𝑑 ℎ𝑣 = 𝐻𝑒𝑎𝑡 𝑇𝑟𝑎𝑛𝑠𝑓𝑒𝑟 𝐶𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑇𝑣 = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑑𝑟𝑦𝑖𝑛𝑔 𝑔𝑎𝑠 𝑇𝑖 = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑙𝑖𝑞𝑢𝑖𝑑/𝑔𝑎𝑠 𝑖𝑛𝑡𝑒𝑟𝑓𝑎𝑐𝑒 The temperature of the drying gas (Tv) is the normally measured dry bulb temperature. At steady state, the temperature of the liquid-gas interface (Tj) is equal to the wet bulb temperature of the drying air. Thus, the drying rate is proportional to the difference between the dry and wet bulb temperatures of the air.
Page - 168
Air Velocity = ____________________ m/sec. Weight of dry sand = _______________ kg. Dry Bulb Temp. Tv oC Wet Bulb Temp. Ti oC (Tv-Ti) oC Time (min)
0
0
0
Wet Sand Weight (kg) Moisture Content XE
𝑋𝐸 =
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐿𝑖𝑞𝑢𝑖𝑑 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑊𝑒𝑡 𝑆𝑎𝑛𝑑 − 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐷𝑟𝑦 𝑆𝑎𝑛𝑑
From the results, plot the drying curves relating moisture constant and time for each test. Differentiate data from, these curves to produce the drying rate-moisture content curves:
Comment upon the results obtained, noting the influence that (Tv - Ti) had upon the drying rate during the constant rate period.
Page - 169
Experiment 15 (FLUIDIZED BED DRIER APPARATUS) Objective: To: 1. Investigate the simple drying of a material to give moisture content and the drying time required. 2. Determine the drying curves to assess the feasibility of fluidized bed drying of a material on an industrial scale. 3. Calculate heat transfer coefficient (It is important in drier design and comparison of fluidized beds with other drying methods).
Equipment Setup / Apparatus: Fluidized Bed Drier Apparatus, Digital Weight Balance, and Wet and Dry Bulb Thermometer.
Reagents: Any suitable solid particles which are wet and need to be dried, Air. Page - 170
Procedure: 1) Determine the optimum bed depth the optimum bed depth is that which can be fluidized at the required temperature by relative high air velocity. The optimum bed depth will vary appreciably with the material-an initial bed depth of about 75mm is typical. 2) Remove any excess water from the solid sample by decanting and / or using a filter pump. 3) Place the sample of material in the jar to an appropriate bed depth. Weigh the jaar alone then with the material. 4) Fix the sealing ring into the groove. 5) Switch on the mains supply and select the drying temperature required (select three temperatures). 6) Note the wet and dry bulb temperatures of the inlet air to the fan and outlet air from the fluidized bed. 7) Weigh the jar with material at 2 minute intervals for about 16 minutes (or as long as it takes to attain constant weight) recording the wet and dry bulb temperature before removing the jar for weighing. Continue until constant weigh is achieved indicating that the equilibrium moisture content has been reached. 8) Record the drying time and moisture content.
Data Analysis: From the results, plot the drying curve relating moisture content as a function of time. Carefully differentiate data from this curve to produce the drying rate - moisture content plot, attempting to identify the points (A, B, C and D) at which the drying passes from one regime to the next.
Page - 171
CALCULATION OF HEAT TRANSFER COEFFICIENT: Heat lost by entering gas = Heat transferred to solids to vaporize the liquid Therefore: 𝑑𝑤 1 = −ℎ𝐴(𝑇𝑎 − 𝑇𝑠 )log 𝑚𝑒𝑎𝑛 × 𝑑𝑡 𝐿 This equation can be integrated to give: ℎ=
(𝑊0 − 𝑊𝑐 )×𝐿 𝑡×𝐴×(𝑇𝑎 − 𝑇𝑠 )log 𝑚𝑒𝑎𝑛
Where: dw/dt = Constant drying rate [kg/s] L = Latent heat of vaporization [J/kg] H = Heat transfer coefficient [W/(m2×oC)] A = Surface area [m2] Ta = Dry bulb air temperature [oC] Ts = Wet bulb air temperature, [oC] Wo = Initial moisture content [kg water/kg dry solid] Wc = Critical moisture content at end of constant rate period [kg water/kg dry solid] t = Constant rate drying time [sec]
Page - 172
Lab Flexes
1. 2. 3. 4. 5. 3. 4. 5. 6. 7. 8. 9. 10.
Lab Notebook Rubric Experiment Performance Rubric General Safety Precautions List of Equipment List of Experiments Gas Diffusion Coefficients Apparatus Ion Exchange Apparatus Batch Distillation Apparatus Continuous Distillation Apparatus Gas Absorption Column Apparatus Liquid-Liquid Extraction Apparatus Tray Drier Apparatus Fluid Bed Drier Apparatus
Page - 173
Page - 174
Page - 175
Page - 176
Page - 177
Page - 178
Page - 179
Page - 180
Page - 181
Page - 182
Page - 183
Page - 184
Page - 185
Page - 186
Material Safety Data Sheets for Chemicals
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Acetone HCl NaOH H2O Methylcyclohexane Toluene CO2 Air NaHCO3 Phenolphthalein Propionic Acid Trichloroethylene Sand
Page - 187
Page - 188
Page - 189
Page - 190
Page - 191
Page - 192
Page - 193
Page - 194
Page - 195
Page - 196
Page - 197
Page - 198
Page - 199
Page - 200
Page - 201
Page - 202
Page - 203
Page - 204
Page - 205
Page - 206
Page - 207
Page - 208
Page - 209
Page - 210
Page - 211
Page - 212
Page - 213
Page - 214
Page - 215
Page - 216
Page - 217
Page - 218
Page - 219
Page - 220
Page - 221
Page - 222
Page - 223
Page - 224
Page - 225
Page - 226
Page - 227
Page - 228
Page - 229
Page - 230
Page - 231
Page - 232
Page - 233
Page - 234
Page - 235
Page - 236
Page - 237
Page - 238
Page - 239
Page - 240
Page - 241
Page - 242
Page - 243
Page - 244
Page - 245
Page - 246
Page - 247
Page - 248
Page - 249
Page - 250
Page - 251
Page - 252
Page - 253
Page - 254
Page - 255
Page - 256
Page - 257
Page - 258
Page - 259
Page - 260
Page - 261
Page - 262
Page - 263
Page - 264
